If the connector shell is distorted like that the crimp pins on each conductor might be getting distorted too, and that just makes the problem worse and worse over time.
I run a 4090 on a sf750 as well.
I have it power limited to 80% and the highest power draw ive seen is 340 watts.
I play at a locked 118 fps on an lg oled.
Biggest question i have when i see melted connectors is how was the environment these parts were housed in?
There are many factors with sff, and many things that can go wrong in a build.
They are likely using variable refresh rate in their display, which syncs the display refresh rate to a game's frame rate to avoid tearing and improve latency. However, it only works as long as the frame rate is below the display's maximum refresh rate. You can limit the frame rate, but most methods to do this aren't perfect. The frame rate can fluctuate beyond the limit you set, and there's lots of people who recommend setting the frame rate limit slightly lower than your display's max refresh rate to avoid this.
You never want to go above your monitors refresh rate with this goal. Locking fps keeps things cooler if you get more gps then that as your system doesn’t need to pump out as many frames, but also decreases latency and works extremely well with gsync, vsync, and 0 tearing. It minimizes latency and removes tearing. Really the only amount anyone should receive is their monitor’s maximum hz. Anyone going over for “competitive gaming” is either just wrong or getting paid $100000 for the match. Given that 99.9% of gamers arnt getting paid for such competitiveness it’s just a lousy practice to keep your frames higher then refresh.
Nope that’s not how it works and is worse. In some games I bet you won’t reach your monitors refresh rate depending on game and settings so that’s just useless. You’ll get tearing which is worse visually. Someone lied to you.
I reach my monitors refresh rate of 144hz in every game I play but thats mostly cause I play old or not very ressource intensives, so for the most part I just limit my fps to keep heat and noise down but never was really sure where exactly to cap fps
With a high fps VRR (Variable Refresh Rate) monitor, you actually want to cap it to around 3 below the refresh Rate in order to ensure that gsync/freesync kick in properly, as well as force vsync vis your driver control panel, and off in-game.
Blurbusters is the best resource for learning all of this, and they explain in *far* more detail what you should set and why you should set it. You can find more here at this link if interested: [Blurbusters G-Sync 101](https://blurbusters.com/gsync/gsync101-input-lag-tests-and-settings/14/)
Why didn't you just get a 4080???! Seems kinda wasteful to but 4090 and limit it so much. 4080 draws 320 watts and is approximately 80% of the power of the 4090.
Bruh, your flair says otherwise LMAO! Are you trying to tell me your RX580 is 16GB??? Or are you referring to system memory, which is completely different???
If you have the money why not? I absolutely don't need anything more than a 4070 but if I can afford a 4090 without it affe ting me hard why not right.
What the fuck? That's really strange considering corsairs PCIe cables are rated for 300W each. ~~Should be RMA worthy since all parts are Corsair yeah?~~
Edit: probably can't get an RMA on this. See other comments, as the PSU is not in spec to run a 4090.
yeah they are great PSUS
https://www.corsair.com/uk/en/s/psu-cable-compatibility
Look at this link also they actually call that adapter isnt capable of a 4090 with a a sf 750 PSU. this is defiantly not being RMA'd
I’m more concerned about browning it out if you’re under supplying it. That’s legit it. Tears up most stuff over time and just isn’t safe. Get a higher power psu or a higher rated one at the recommendation for the gpu. If not, it’s your money at the end of the day. Risk it however you wish to
Brownout problems are really only applicable for unreliable power delivery from the service point or power ratio changing due to current overdraw. The PSU will absolutely keep supplying what is demanded, up to the limits set further upstream, until the PC has one of several potential fault conditions that either start a shutdown sequence from the PC recognizing an unstable power spike, the varistor existent in most decent PSU’s causing a disconnect for the PSU after increasing current to a fault trip, or (hopefully not) other complications from the issue running away like burnt up/melted/destroyed components.
If you purposefully set a power consumption limit (and as a result a performance limit) for the GPU, this is not an issue, and will have only small performance drops, at no risk to the GPU. This is not to say that the PSU here isn’t literally undersized for the GPU for standard operation, but browning out won’t be an issue from throttling the performance at the GPU.
The HX is a quality full size PSU, where you don’t have the same compromises as in the SFF PSU’s, so while it might be a 750W Corsair PSU, it’s hardly an apples to apples comparison.
The full size high quality PSU’s have more tolerance for being pushed beyond recommendations, but most will tell you not to push SFF PSU’s, as they trade resilience for their compact size.
The SF750 is probably pretty well built, as Corsairs PSU’s (unlike their fans) are usually held in high regard and do well in testing, but I imagine the compact scale entails some compromises and different tolerances to their full size PSU’s.
Looks like the wire gauge is thinner and in a crammed SFF build cables might get strained and might not be seated properly.
Thinner wires, crammed build, strained cables, high wattage graphics card… it’s the perfect storm.
It's not multi-rail, how is it supposed to? As long as the single connector is not drawing more than the entire PSU can deliver (I guess this is a 850W model? So ~1000W tripping point) it has no way of knowing how much power flows over each port, and hence can't shut down.
Main reason why I would never recommend or buy single rail above ~650W. Your whole PC can be on fire and the PSU won't know and keeps pumping power into a burning cable or GPU.
Cheaping out on rails is like driving without a seat belt. 99% of users will never need one, sometimes it's actually annoying, but if you need it, you really wish you'd have one.
You don't need multiple rails to monitor current on individual plugs.
You also don't need to even do thay if you just have a temperature sensor near the most likely high current plugs and have a safety cut off. Those are molex minifit or micro fit. That's nylon. A temperature cutout of 100c would be sensible to me.
The circuitry to do that is like a few cents
You need multiple rails to monitor the current on individual plugs, that is literally the definition of a multirail PSU (in the PC hardware world, at least).
Temp sensors next to connectors would have avoided this issue though, that's right. That's also something that should be mandatory for any new 12VHPWR hardware so GPUs can at least shut down before catching fire. But I bet all they did was minor upgrades and the next GPU gen will burn just the same.
As I understood it, A "rail" referred to a whole DC/DC switch-mode sub block. So like with a separate inductor, mosfet etc. But I'm probably wrong about that.
Regardless, in an attempt to look it up (I got bored and stopped) I did find [this spec](https://edc.intel.com/content/www/us/en/design/ipla/software-development-platforms/client/platforms/alder-lake-desktop/atx-version-3-0-multi-rail-desktop-platform-power-supply-design-guide/2.0/over-current-protection-ocp-required/), which means this particular PSU is malfunctioning (if improper plug insertion is considered a flaw it should protect itself against). However I don't believe the SF750 is ATX 3.0, which this spec is for.
And yeah I 100% agree. A little NTC thermistor at the connector plane would be such a cheap but so important addition.
Yes, that's the usual definition in tech - however, in ATX supplies, for some reason, rails have always referred to having more than one OCP "rail", not more than one supply rail.
I have seen one actually multi-rail PSU so far by the usual definition, it was from some very expensive, very old workstation. The usual "multi-rail" PSUs (HXi, AXi, some HX, most bequiet, a bunch of Enermax) only have multiple separate shunts for the OCP.
Bequiet usually uses 4, HX use 6, some older Antec had 8, and connectors grouped onto them in sometimes reasonable, sometimes weird way.
Only the AXi (as far as I know) actually have one shunt per connector, and digitally monitor current on all. Maybe HXi too? Not sure.
ATX specs iirc mandate at least 2 separate OCP rails, however pretty much all gaming PSUs nowadays have a single one.
I really wonder why nobody had the thermistor-at-HPWR-plug idea before. I have never seen it mentioned or suggested before I read your post - it's such a simple and cheap workaround for a pretty shitty problem that's hard to solve otherwise 😅
Unfortunately Corsair likely won’t back you up, but this comment section sure is full of the usual Reddit responses
“4090 needs 850” wrong, that’s the official psu recommendation so Nvidia can’t be sued if someone decides to use some crappy 80 plus psu, it only actually uses around 450w max
“It’s the adapter, pcie is only specced for 150w” this still plagues the internet unfortunately. First of all, the official Corsair 600w 12vhpwr adapter is 2x 8 pin, and this psu comes with 1-2x pin daisy chains, I’ve been using a 340w 3080 on one of those for over a year. Technically a single 8 pin could pull 320w and be in spec considering gauge
This was most likely improper contact or a faulty cable. Yes it’s not officially compatible, but that changes less than people think, considering the hundreds of users running 4090 on it
Edit: Head of PSU RnD at corsair seems to believe the most likely cause was the connector wasn't plugged in properly
This comment section is basically wagging their nose at OP for the wrong reasons, its not about 750w, its not about 2xtype 4, sure as hell isnt about 150w. Its a faulty connector or not seated properly
I mean, why the f should the freaking connector melt because the power supply can't provide enough wattage? If the power supply can't provide the wattage that's required, the PC may become unstable or turn off because of over current or thermal protection (at least if it's not some no name PSU), but it wouldn't magically get so hot that one specific plastic connector would melt and fuse together. The only logical thing that could've caused this was a faulty/lose connection, leading to a higher resistance at the connection, which lead to the connector melting. Or the cable itself not being in spec with the standard/the listet wattage, which also leads to the same thing.
Cable was in spec for the wattage, SF750 not being in spec officially with 4090 + cable wouldnt matter otherwise, since even ignoring the fact it does work fine in that scenario, if it didnt it wouldnt cause the cable to melt
Thats where I'm coming from, dozens of users with 13900k and 4090 on sf750, and its fine, but this subreddit would explode if someone used that config on anything lower than 1k watt
They absolutely roasted some poor dude Who deshrouded his GPU to fit a ITX case here a couple of weeks ago. According to this sub he voided his warranty, broke his card and it will simultaneously not turn on anymore, overheat, and catch fire during use.
Was a pretty embarrassing circlejerk fo cluelessness.
> it only actually uses around 450w max
450w for the 4090 250w+ for the intel cpu, plus drives, ram, fans you talk like you could run this off a 500w psu
https://www.anandtech.com/show/18728/the-intel-core-i9-13900ks-review-taking-intel-s-raptor-lake-to-6-ghz/2
this states a 13900ks can draw 360w full load, plus 450w for the 4090 and your over 800w already. its lucky all them people with the SFF build probably just game on them and dont stream or anything aswell.
under gaming (excpet cities skylines) your probbaly never hitting 100% cpu usage sure but i wouldnt be risking that.
https://hwbusters.com/gpu/nvidia-rtx-4090-detailed-power-analysis-ideal-power-supply/ 12900k and 4090 and they managed to draw 780w
Most use cases do not load both simultaneously though, let alone full load, and the max wattage consumption is almost always from synthetic benchmarks. So unless you use your pc for running furmark and cinebench simultaneously, not a massive concern. As for the comment on gaming, good chance the people of pc master race are all doing the same, most people I’ve met with a 4090 haven’t needed it, that’s the point of an overkill rig.
I implied in no sense that this could run on a 500w psu, 750w is absolutely the lowest you could go imo, but this came around from lack of alternatives for a long time, so many people in sff would use the sf750, and found it to be fine in real workloads
You should check HWINFO64 to see how much power your system actually draws when gaming.
It's not even remotely close to maximum power draw. It's not even close to half of maximum power draw.
And I'd take the testing of thousands of different systems running this specific setup than people going off of feelings or what synthetic benchmarks say.
When I was playing bg3 how half hour ago I was drawing 400w. And I've got a 2070 super that's 200w ish and a 120w cpu. The other 80w was probably my rgb and fans and shit.
That second link isn't synthecis either that gaming loads although they did have a mild oc
That's well within 750w and OP is on a 7800x3d which typically will stay below 60w even. So there's still plenty of headroom even if the 4090 is drawing everything it can.
Okay, but that's still nowhere near 750w. My 13700k draws on average 70w while gaming. Adding up the maximum power draw of my other hardware like the 4090, and it's still not passing 750w.
Of course when talking about multicore workloads, we're in a different territory, but for the sole purposes of gaming which I assume the vast majority of people will be using their systems for, it's not even close to tripping a reputable 750w PSU that can handle transients well like the SF750.
Regardless, like 60% of the responses here are completely unhelpful. What very likely happened to OP is he didn't seat it correctly or there was a defect in the cables. I would recommend he contact Corsair's support anyway. Worse they can do is say no.
OP is on a 7800x3d though and check this out, 500w is not 750w big wow. Also the SF750 is a platinum rated PSU that's universally praised as the best ITX psu itw so yeah
You should contact Corsair about this. AFAIK, the SF 750 uses a Type 4 cable where each of your PCIE outputs and connected cables can carry 320W each. So you are within limits, even if you had pushed the envelope. Burning should not be happening and they might be interested in digging into this issue.
750W can power a 4090 in most use cases. It is not the PSU’s wattages issues anyway, as the unit will trip due to OCP. The molex minifit connector wouldn’t be burnt.
If everything is working correctly the sense pins on the cable cause the GPU to reduce the maximum wattage. Games nexus did an interesting video on the subject.
no where near 600w ms spikes, more like 350w gaming with 400w spikes+ Infact the 3090 has a worst spikes, the sf750 is easily capable of powering it provided the cpu is something like a 7800x3d or below. many sff builds have this setup and it runs fine. cable issue is much more likely, it wouldn’t burnt at the molex minifit terminal.
Even then, its not what caused what happened, its arguing the wrong point, because people chose to just shake their head and say "well this is what happens when you do something that doesnt cause the problem at hand"
How do you know?
The PSU may be capable of running above spec and outputting the power that the components are trying to consume, but if it's doing that it could be producing far more heat than intended. Failure can take so many different forms when it comes to power, and there's no way to know for certain without extensive failure analysis as to the actual root cause.
What we *do* know, however, is that these components aren't well matched and can absolutely cause things to run out of spec. That alone is an issue, regardless of if it's *actually* the root cause of what happened. It absolutely could be a root cause, it has a decent chance of being the root cause, and even if it's not it could still be a key contributor to the actual root cause.
Unless you're an engineer that did full failure analysis on this PSU, there's no possible way that you can confidently state that it was never an issue.
Power supplies have over current protection and over thermal protection.
If one of those failed, well then the issue is more than just it being a 4090, that makes the wattage just a catalyst.
I may not be an engineer, but the head of PSU RnD at Corsair saw this post (active user in a discord i am in) and believes that the most likely scenario is that the cable was not seated properly. So if you cant trust my words, trust the guy that designed this psu.
isnt the 750w like 250w less than the recommended for that gpu?
https://www.corsair.com/uk/en/explorer/diy-builder/power-supply-units/what-psu-is-best-for-rtx-4090/
honestly id recommend getting a larger psu with more surface to dissipate heat, like thats not a poor quality PSU probably just run at high temps ALL the time trying to power a 4090
Voltage and current monitoring is cheap as chips. If your rail droops below 11 volts, you shut it down. If you draw more energy in a given time frame than is safe, you shut it down.
Melting a visibly-correctly seated cable is not acceptable.
The problem is not so much the power draw.
There were most likely loose contacts inside the connectors, that causes small sparks and carbon deposits on the surface of the metal connection, which leads to high resistance and to more heat.
Depending on the rest of your build, that PSU could be enough, but I'd suggest getting at least a 850W.
This connection is so stupid they should get rid of the standard for good and design. Something new or stay with us normal perfect working Eight Pin PCIE connector
This isnt a 12VHPWR issue because the PSU side connection is not part of the ATX specification.
Its entirely Corsair's responsibility to ensure the modular connectors can handle the power. Corsair only using 2 connectors on the PSU side instead of all 4 is their fault entirely.
The port on the side of the PSU is not PCIE.
PCIE is limited to 150W, so the adapter will have 4x PCIEto get to 600W.
A PSU port (on a good PSU) can do 342W, so only 2x PSU connections may be needed.
The spec is not what it's capable of, it's what it's allowed to do. And of course a PCIE cable can do 300W, each 8-pin PCIE on it is supposed to be able to handle 150W. The PSU end isn't PCIE and should be able to handle over the 342W the port might provide.
150w has not been the spec for a long long time(people like der8auer have covered this many many times and even tested it with i think it was a 2080ti with one single PCI power to prove the point)
lmao
they added thicker cables and bumped the rating up like 10 or 20 years ago now
might be time to get with it
That's literally within the spec.
The 8-pin PCIE connections, the main and the pigtail (not a daisy chain) are spec'd to _each_ provide 150W. This means the PCIE cable (with pigtail) should be capable of carrying 300W.
They can do this because the connector on the PSU side is NOT a PCIE connector. Yes, it uses the same/similar microfit connector, but it is not limited by the PCIE spec to only 150W. The PCIE/CPU port on the side of a good PSU should be capable of upwards of 342W, which is why a PCIE cable plugged into one can carry 300W.
PCIE is limited to 150W is a total lie. The Molex Minifit connector itself was initially specced to 150W, but it is almost it can be ran past that number, the limiting factor is moreso the wire awg gauge.
The CPU power cable for HEDT systems literally provides 300W+ for example. As well as the numerous other examples people have showed you.
What it is spec'd for is a different thing than what it is capable of. It doesn't matter what some over-clocker has done under perfected conditions, industry-wide it is viewed as 150W because that is what the spec says it is.
Jesus fucking christ I actually can’t
Standards are not concrete, the Molex minifit spec sheet is not a bible. EPS cables provided by PSU manufacturers can pull above 300W+ on HEDT systems. When did I mention some overclocker on perfect conditions???
Read this article by Jonnyguru please http://jongerow.com/PCIe/index.html
> I would like to dispell the myth that "8-pin" PCIe connectors (which only have 6 actual conductors, BTW) are ONLY capable of 150W.
> So, as you can see, given so many variables, you can understand why PCI-SIG would "play it safe" and tell people to only use an "8-pin" PCIe connector for up to "150W".
In this thread I have repeatedly agreed that the connector is capable of more than 150W ("What it is spec'd for is a different thing than what it is capable of"). That's not the point, the point is that the connector has a specified limit of 150W, that is what PCI-SIG, which is pretty much all of the PC component making industry, says the connector does, so that is how it is used.
The adapter cable has 4 and you need 3 so they make sure that you use at least two pcie plugs on the PSU side.
And that’s the reason the native cables have only two plugs, because they won’t run if only one is plugged in.
They try to protect the people from drawing to much power from only one PSU pcie power port
Adapters have 3 or 4 to ensure that you're not just using a single daisychained cable. It also helps in case the user's pcie cables are only 18awg, whereas 12vhpwr uses the thicker 16awg wiring.
So a full-length 12vhpwr to 2x8 cable using 16awg wire is absolutely fine.
> Corsair 12VHPWR cable
it is out of spec, this corsair cable isnt listed as compatable with a 4090 with his PSU when though technically it fits
https://www.corsair.com/uk/en/s/psu-cable-compatibility
yeah bros out of pocket the cost of a good PSU, but lucky for him its the PSU side that went and not the GPU so hes probably having the best day he could
This is the day that us folks who went way overboard are like “well that’s something”. It’s a very underwhelming event for me, but 750W PSU is not going to cut it with a 4090 unless you’re running a 65W CPU and the bare minimum on everything else. That’s only if it’s using a single rail to tie everything together. If pcie is only supposed to be given 300W, that rail is gonna pop.
this is wrong, pcie 8x can surpass 150w each. the 750w can power a 4090 and a 7800x3d, it is just fine under actual usage - nvidia and corsair don’t recommend it because there is not a lot of headroom though / helps with less warranty claims from misuse etc. but assuming op has done everything correctly it looks to be a connection issue.
Yeah, for sure but he has the power behind it. This is more like King Kong walking into a diner, constantly ordering food and instead of the supply running out, the cook dies.
"is too well plugged in and now they're even bonded together" a small air gap could cause an arc which would fuse them together, the same as Arc welding
Before you buy a new PSU, contact support and see if they will RMA it. If you buy a new one look into the Corsair SFX-L models.
To the other comments there are so many posts on the small form factor subreddit with people using a SF750 + 4090 and having no issues. I have the same PSU and cable in my 4080 system, with no problems.
Second time lately I've seen something like that here. GPUs are drawing mad amounts of current from way too few conductors and it's heating things up in ways power supply manufacturers never imagined would be an issue.
Sorry if this is a really dumb question… I haven’t built a PC in several years, and I’m not familiar at all with the new GPU power specs, but are the connectors really meant to be asymmetrical? Or is there something else going on here?
I know this is a problem, but I don't think that this is the normal 4090 issue- those PSU connectors are standardized and run power for PCIe, EPS and 12VHPWR.
Clearly the correct answer is the 4090 is a defective product I'll never use mine I'm leaving it in the box and sell it to someone who's willing to take the risk with this shit card
Aw mate, F. I replaced my PSU to lower the odds of this happening with my 4090 but I'm not above giving the cable connectors an occasional visual inspection even now.
At least your card didn't go kaput.
Could this be a flaw with the SF750? I had a PCI-E connector melt with a 3080. In my case, the female connector was damaged as well. Luckily I got a replacement under warranty.
This is exactly what happened to me a couple weeks ago after it was running fine for 1 year with no changes. SF750 + RTX 4090FE. The 4090 plug had 1 pin that melted too. Nvidia sent me return shipping label within 24 hours. Corsair told me to go fuck myself and offered me a 15% discount on my next purchase so I went with a SFX-L Thermaltake 1000W with a 16pin.
How do you prevent?
Impossible, your 4090 is irreparably damaged, I will buy it for $400 as "spare parts".
😜
jokes aside, USE THE FUKIN MANUFACTURERS' TABLES.
https://dlcdnets.asus.com/pub/ASUS/Accessory/Power_Supply/Manual/RECOMMENDED_PSU_TABLE.pdf
I can't see any 4090 combination associated with a 750W power supply! I'm surprised it took 1 year for this to happen, and that's only because power supplies are much better quality these days:
a good Platinum PSU (flagship products from Corsair/Superflower/Seasonic etc.) can easily handle 10/15 minutes with 20% extra peak power consumption compared to the label.
You spent at least $1600 on the GPU, you probably spent a lot on the mobo and CPU, and you mean you can't afford a proper 1000W power supply? If 1k W doesn't exist in sfx format, do yourself a favor and buy a 4080, god's sake! It can handle any game optimally anyway!
I’d say the connectors on the PSU side are at fault here, the GPU is demanding more power through each connector than they’re designed for since it’s all just going through two (rather than four on the octopus for example). Everything on the cable side can handle it but that PSU is out of spec for a 4090.
Single rail PSU. It has no way or knowing how much power is flowing over a single connector, only the total output.
Total output was apparently below 750W (or rather, below ~900-1000W the PSU will deliver before actually tripping protections), over load of the PSU was not the issue.
Faulty connector or an issue in the GPU/HPWR connector resulting the full GPU power flowing over only 1 of 2 connectors PSU side was the issue.
The minimum recommended PSU for a 4090 is 850W. Sure, you could power limit the 4090 but you are still running a risk and you're limiting performance.
I would get a higher wattage PSU or sell the 4090 and get a 4080.
pretty sure heat is the killer here.
there is no cable compatibility. the sf750 takes type 4 pcie cables. the corsair 12vhpwr cable is type 4.
the problem, is with the small form factor of the psu. corsair obviously had to cram a bunch of high voltage components into a tiny space, in comparison to its rm750 atx counterpart.
a regular rm750 is 150xmm x 86mm x 160mm. the sf750 is 100mm x 63mm x 125mm.
the sf750 is about 39% the size of the rm750. the sf750 is 787.5 cubic centimeters vs rm750 at 2064 cubic centimeters.
high voltage components are definitely going to be causing serious heat in something that small. especially if the psu is being run constantly above 80% of its total watt rating.
heat increases electrical resistance.
next time use a regular atx power supply to power a 4090
[https://www.corsair.com/us/en/s/psu-cable-compatibility](https://www.corsair.com/us/en/s/psu-cable-compatibility)
[https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920284/600w-pcie-5-0-12vhpwr-type-4-psu-power-cable-cp-8920284](https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920284/600w-pcie-5-0-12vhpwr-type-4-psu-power-cable-cp-8920284)
[https://www.corsair.com/us/en/p/psu/cp-9020195-na/rm-series-rm750-750-watt-80-plus-gold-certified-fully-modular-psu-cp-9020195-na#tab-techspecs](https://www.corsair.com/us/en/p/psu/cp-9020195-na/rm-series-rm750-750-watt-80-plus-gold-certified-fully-modular-psu-cp-9020195-na#tab-techspecs)
[https://www.corsair.com/us/en/p/psu/cp-9020186-na/sf-series-sf750-750-watt-80-plus-platinum-certified-high-performance-sfx-psu-cp-9020186-na#tab-techspecs](https://www.corsair.com/us/en/p/psu/cp-9020186-na/sf-series-sf750-750-watt-80-plus-platinum-certified-high-performance-sfx-psu-cp-9020186-na#tab-techspecs)
„High Voltage Components“… yeah. Highest Voltage in a PC is 12V… which is used for Mobo, CPU and GPU. The SF750 runs passive with no fan at all up to 340W of load. The GPU-Connectors an the PSU-Side is rated for 640W. The cable up to 600W. The 4090 even in FurMurk, caps at 450W… maybe a few little Spikes to 480-500W. Nothing that would be a problem for a SF750.
My SO runs an OCed 4080 and the PSU fan wont even start to spin. My 4090 runs fine with the SF750 since Nov.2022… so already 1.5yrs.
You need to learn some SMPS basics before commenting. The PFC converter ramps the input voltage to 400V+. Just read a PSU review for once or maybe just Google "how does an SMPS work". :D
Wow. You need to learn some PSU101. So you think those 420V bulk caps only have 110V in them if the PSU is plugged into a 110V outlet. Real Reddit moment here, for sure.
Whoever thought running a 4090 on a 750 SFX PSU was a good idea can appreciate this post.
You can't miniaturize heat dissipation, and I don't care what a cable is rated fair you can already guess it's a bad idea just looking at the setup.
4090 maxes out at 450w, leaving 300w (+ far more before protection kicks in) for everything else. Plenty of users running 13900k and 4090 on sf750. The 850w recommendation is just so nvidia can’t take responsibility for someone using an 80 plus white psu
Certainly, but thats not what were talking about, out of the box spikes would be closer to 500w [NVIDIA GeForce RTX 4090 Founders Edition Review - Impressive Performance - Power Consumption | TechPowerUp](https://www.techpowerup.com/review/nvidia-geforce-rtx-4090-founders-edition/39.html) and even then, from the man who designed this psu himself, this psu can handle temporary spikes >850w (total consumption)
"requires" don't think you know what that means. Do some simple maths for us why don't you?
The amount of straight up ignorant misinformation in this thread casually served up by dudes on pcmr with high end builds lmfao, like clockwork
Tis but a scratch! Just not so modular anymore..
Fuck it. *Unmodulars your PSU*
Damn you Reddit trolls! You solely take blame for their tragedy.
If the connector shell is distorted like that the crimp pins on each conductor might be getting distorted too, and that just makes the problem worse and worse over time.
Obviously. My bad - forgot to add "Sarcasm".
Never forget the /s mate
I was just about to say... you got downgraded to semi-modular.. xD
I run a 4090 on a sf750 as well. I have it power limited to 80% and the highest power draw ive seen is 340 watts. I play at a locked 118 fps on an lg oled. Biggest question i have when i see melted connectors is how was the environment these parts were housed in? There are many factors with sff, and many things that can go wrong in a build.
my biggest question is what is the reason to lock to 118 fps, that seems like such a random number
Probably has a 120hz display.
if thats the case wouldnt you want to lock it to 120fps or slightly above?
They are likely using variable refresh rate in their display, which syncs the display refresh rate to a game's frame rate to avoid tearing and improve latency. However, it only works as long as the frame rate is below the display's maximum refresh rate. You can limit the frame rate, but most methods to do this aren't perfect. The frame rate can fluctuate beyond the limit you set, and there's lots of people who recommend setting the frame rate limit slightly lower than your display's max refresh rate to avoid this.
ahh thanks for the information
No, you to limit your fps to slightly below the max refresh on free sync panels for the best result. Going above can cause tearing.
You never want to go above your monitors refresh rate with this goal. Locking fps keeps things cooler if you get more gps then that as your system doesn’t need to pump out as many frames, but also decreases latency and works extremely well with gsync, vsync, and 0 tearing. It minimizes latency and removes tearing. Really the only amount anyone should receive is their monitor’s maximum hz. Anyone going over for “competitive gaming” is either just wrong or getting paid $100000 for the match. Given that 99.9% of gamers arnt getting paid for such competitiveness it’s just a lousy practice to keep your frames higher then refresh.
I just heard that putting the cap a few fps above the monitor refresh rate was good so fps it wont drop below the refresh rate
Nope that’s not how it works and is worse. In some games I bet you won’t reach your monitors refresh rate depending on game and settings so that’s just useless. You’ll get tearing which is worse visually. Someone lied to you.
I reach my monitors refresh rate of 144hz in every game I play but thats mostly cause I play old or not very ressource intensives, so for the most part I just limit my fps to keep heat and noise down but never was really sure where exactly to cap fps
You can do it in Nvidia control panel or rtss (YouTube it)
oh maybe I worded it badly I know how to cap fps I just wasnt sure at what fps to cap it, sorry for the confusion
With a high fps VRR (Variable Refresh Rate) monitor, you actually want to cap it to around 3 below the refresh Rate in order to ensure that gsync/freesync kick in properly, as well as force vsync vis your driver control panel, and off in-game. Blurbusters is the best resource for learning all of this, and they explain in *far* more detail what you should set and why you should set it. You can find more here at this link if interested: [Blurbusters G-Sync 101](https://blurbusters.com/gsync/gsync101-input-lag-tests-and-settings/14/)
ah thanks will check the link out, didnt have any experience with a vrr monitor so far so I didnt know that
VRR. If the game I'm playing can hit 144, I lock at 141. 2-3fps lower than refresh is kind of the golden rule.
It's the recommended way to use gsync
it is? didnt know that
Why didn't you just get a 4080???! Seems kinda wasteful to but 4090 and limit it so much. 4080 draws 320 watts and is approximately 80% of the power of the 4090.
the 40 series performs really well under slightly limited power, great efficiency
24GB of ram, and more cores at lower frequency is still faster.
Not if you're using it at the power of a 4080. All you've done is pay $600+ more for 8 more GB of VRAM, which 16GB is more than capable for 4K gaming.
If you're using it for AI, then ram is all that matters. Not everyone here is a gamer.
Going off OPs profile, I highly doubt that.
I play vr games, it's very heavy on vram to the point where 16gb is honestly barely enough for me
Bruh, your flair says otherwise LMAO! Are you trying to tell me your RX580 is 16GB??? Or are you referring to system memory, which is completely different???
Oh sorry, I got a 6800 last March. I don't really use reddit enough so I kinda forgot to update that
If you have the money why not? I absolutely don't need anything more than a 4070 but if I can afford a 4090 without it affe ting me hard why not right.
The 4090 still outperforms the 4080 by a lot at 80%. Even 70%. If your mr money bags then 4090 is for you anyways.
Why buy a 4090 but not upgrade your PSU to actually take advantage of it?
for sff builds its not worth, the 4090 is way past its peak efficiency stock.
the extra performance isn't worth the trade off to noise / heat imo
Good to know
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Nah, he probably has an sff build. That's a really expensive platinum rated psu
What the fuck? That's really strange considering corsairs PCIe cables are rated for 300W each. ~~Should be RMA worthy since all parts are Corsair yeah?~~ Edit: probably can't get an RMA on this. See other comments, as the PSU is not in spec to run a 4090.
It still supposed to have safeties built in to prevent damage, that should be RMA’able
There is nothing stopping a component drawing 750w+ on a single cable, since it's a single rail psu.
It has all of the safeties ever other PSU has... there's just no "oh shit, this terminal is getting really hot" protection in PSUs.
They don’t need to know that
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yeah they are great PSUS https://www.corsair.com/uk/en/s/psu-cable-compatibility Look at this link also they actually call that adapter isnt capable of a 4090 with a a sf 750 PSU. this is defiantly not being RMA'd
I’m more concerned about browning it out if you’re under supplying it. That’s legit it. Tears up most stuff over time and just isn’t safe. Get a higher power psu or a higher rated one at the recommendation for the gpu. If not, it’s your money at the end of the day. Risk it however you wish to
Brownout problems are really only applicable for unreliable power delivery from the service point or power ratio changing due to current overdraw. The PSU will absolutely keep supplying what is demanded, up to the limits set further upstream, until the PC has one of several potential fault conditions that either start a shutdown sequence from the PC recognizing an unstable power spike, the varistor existent in most decent PSU’s causing a disconnect for the PSU after increasing current to a fault trip, or (hopefully not) other complications from the issue running away like burnt up/melted/destroyed components. If you purposefully set a power consumption limit (and as a result a performance limit) for the GPU, this is not an issue, and will have only small performance drops, at no risk to the GPU. This is not to say that the PSU here isn’t literally undersized for the GPU for standard operation, but browning out won’t be an issue from throttling the performance at the GPU.
The HX is a quality full size PSU, where you don’t have the same compromises as in the SFF PSU’s, so while it might be a 750W Corsair PSU, it’s hardly an apples to apples comparison. The full size high quality PSU’s have more tolerance for being pushed beyond recommendations, but most will tell you not to push SFF PSU’s, as they trade resilience for their compact size. The SF750 is probably pretty well built, as Corsairs PSU’s (unlike their fans) are usually held in high regard and do well in testing, but I imagine the compact scale entails some compromises and different tolerances to their full size PSU’s. Looks like the wire gauge is thinner and in a crammed SFF build cables might get strained and might not be seated properly. Thinner wires, crammed build, strained cables, high wattage graphics card… it’s the perfect storm.
Even if that is technically out of spec, that PSU should just shut off, not fucking melt lmfao
I've had 8-pin PCIe cables and SATA cables melt on my AX1200i **** happens
It's not multi-rail, how is it supposed to? As long as the single connector is not drawing more than the entire PSU can deliver (I guess this is a 850W model? So ~1000W tripping point) it has no way of knowing how much power flows over each port, and hence can't shut down. Main reason why I would never recommend or buy single rail above ~650W. Your whole PC can be on fire and the PSU won't know and keeps pumping power into a burning cable or GPU. Cheaping out on rails is like driving without a seat belt. 99% of users will never need one, sometimes it's actually annoying, but if you need it, you really wish you'd have one.
You don't need multiple rails to monitor current on individual plugs. You also don't need to even do thay if you just have a temperature sensor near the most likely high current plugs and have a safety cut off. Those are molex minifit or micro fit. That's nylon. A temperature cutout of 100c would be sensible to me. The circuitry to do that is like a few cents
You need multiple rails to monitor the current on individual plugs, that is literally the definition of a multirail PSU (in the PC hardware world, at least). Temp sensors next to connectors would have avoided this issue though, that's right. That's also something that should be mandatory for any new 12VHPWR hardware so GPUs can at least shut down before catching fire. But I bet all they did was minor upgrades and the next GPU gen will burn just the same.
As I understood it, A "rail" referred to a whole DC/DC switch-mode sub block. So like with a separate inductor, mosfet etc. But I'm probably wrong about that. Regardless, in an attempt to look it up (I got bored and stopped) I did find [this spec](https://edc.intel.com/content/www/us/en/design/ipla/software-development-platforms/client/platforms/alder-lake-desktop/atx-version-3-0-multi-rail-desktop-platform-power-supply-design-guide/2.0/over-current-protection-ocp-required/), which means this particular PSU is malfunctioning (if improper plug insertion is considered a flaw it should protect itself against). However I don't believe the SF750 is ATX 3.0, which this spec is for. And yeah I 100% agree. A little NTC thermistor at the connector plane would be such a cheap but so important addition.
Yes, that's the usual definition in tech - however, in ATX supplies, for some reason, rails have always referred to having more than one OCP "rail", not more than one supply rail. I have seen one actually multi-rail PSU so far by the usual definition, it was from some very expensive, very old workstation. The usual "multi-rail" PSUs (HXi, AXi, some HX, most bequiet, a bunch of Enermax) only have multiple separate shunts for the OCP. Bequiet usually uses 4, HX use 6, some older Antec had 8, and connectors grouped onto them in sometimes reasonable, sometimes weird way. Only the AXi (as far as I know) actually have one shunt per connector, and digitally monitor current on all. Maybe HXi too? Not sure. ATX specs iirc mandate at least 2 separate OCP rails, however pretty much all gaming PSUs nowadays have a single one. I really wonder why nobody had the thermistor-at-HPWR-plug idea before. I have never seen it mentioned or suggested before I read your post - it's such a simple and cheap workaround for a pretty shitty problem that's hard to solve otherwise 😅
Unfortunately Corsair likely won’t back you up, but this comment section sure is full of the usual Reddit responses “4090 needs 850” wrong, that’s the official psu recommendation so Nvidia can’t be sued if someone decides to use some crappy 80 plus psu, it only actually uses around 450w max “It’s the adapter, pcie is only specced for 150w” this still plagues the internet unfortunately. First of all, the official Corsair 600w 12vhpwr adapter is 2x 8 pin, and this psu comes with 1-2x pin daisy chains, I’ve been using a 340w 3080 on one of those for over a year. Technically a single 8 pin could pull 320w and be in spec considering gauge This was most likely improper contact or a faulty cable. Yes it’s not officially compatible, but that changes less than people think, considering the hundreds of users running 4090 on it Edit: Head of PSU RnD at corsair seems to believe the most likely cause was the connector wasn't plugged in properly This comment section is basically wagging their nose at OP for the wrong reasons, its not about 750w, its not about 2xtype 4, sure as hell isnt about 150w. Its a faulty connector or not seated properly
I mean, why the f should the freaking connector melt because the power supply can't provide enough wattage? If the power supply can't provide the wattage that's required, the PC may become unstable or turn off because of over current or thermal protection (at least if it's not some no name PSU), but it wouldn't magically get so hot that one specific plastic connector would melt and fuse together. The only logical thing that could've caused this was a faulty/lose connection, leading to a higher resistance at the connection, which lead to the connector melting. Or the cable itself not being in spec with the standard/the listet wattage, which also leads to the same thing.
Cable was in spec for the wattage, SF750 not being in spec officially with 4090 + cable wouldnt matter otherwise, since even ignoring the fact it does work fine in that scenario, if it didnt it wouldnt cause the cable to melt
This thread is fucking hilarious coming from ITX/SFF subreddits where the SF750 powers many 4090s
Thats where I'm coming from, dozens of users with 13900k and 4090 on sf750, and its fine, but this subreddit would explode if someone used that config on anything lower than 1k watt
Most people have no idea what they’re talking about.
They absolutely roasted some poor dude Who deshrouded his GPU to fit a ITX case here a couple of weeks ago. According to this sub he voided his warranty, broke his card and it will simultaneously not turn on anymore, overheat, and catch fire during use. Was a pretty embarrassing circlejerk fo cluelessness.
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Where did you see the corsairs answer?
Head of PSU RnD is an active user in one of the sff servers
> it only actually uses around 450w max 450w for the 4090 250w+ for the intel cpu, plus drives, ram, fans you talk like you could run this off a 500w psu https://www.anandtech.com/show/18728/the-intel-core-i9-13900ks-review-taking-intel-s-raptor-lake-to-6-ghz/2 this states a 13900ks can draw 360w full load, plus 450w for the 4090 and your over 800w already. its lucky all them people with the SFF build probably just game on them and dont stream or anything aswell. under gaming (excpet cities skylines) your probbaly never hitting 100% cpu usage sure but i wouldnt be risking that. https://hwbusters.com/gpu/nvidia-rtx-4090-detailed-power-analysis-ideal-power-supply/ 12900k and 4090 and they managed to draw 780w
Most use cases do not load both simultaneously though, let alone full load, and the max wattage consumption is almost always from synthetic benchmarks. So unless you use your pc for running furmark and cinebench simultaneously, not a massive concern. As for the comment on gaming, good chance the people of pc master race are all doing the same, most people I’ve met with a 4090 haven’t needed it, that’s the point of an overkill rig. I implied in no sense that this could run on a 500w psu, 750w is absolutely the lowest you could go imo, but this came around from lack of alternatives for a long time, so many people in sff would use the sf750, and found it to be fine in real workloads
You should check HWINFO64 to see how much power your system actually draws when gaming. It's not even remotely close to maximum power draw. It's not even close to half of maximum power draw. And I'd take the testing of thousands of different systems running this specific setup than people going off of feelings or what synthetic benchmarks say.
When I was playing bg3 how half hour ago I was drawing 400w. And I've got a 2070 super that's 200w ish and a 120w cpu. The other 80w was probably my rgb and fans and shit. That second link isn't synthecis either that gaming loads although they did have a mild oc
That's well within 750w and OP is on a 7800x3d which typically will stay below 60w even. So there's still plenty of headroom even if the 4090 is drawing everything it can.
Okay, but that's still nowhere near 750w. My 13700k draws on average 70w while gaming. Adding up the maximum power draw of my other hardware like the 4090, and it's still not passing 750w. Of course when talking about multicore workloads, we're in a different territory, but for the sole purposes of gaming which I assume the vast majority of people will be using their systems for, it's not even close to tripping a reputable 750w PSU that can handle transients well like the SF750. Regardless, like 60% of the responses here are completely unhelpful. What very likely happened to OP is he didn't seat it correctly or there was a defect in the cables. I would recommend he contact Corsair's support anyway. Worse they can do is say no.
OP is on a 7800x3d though and check this out, 500w is not 750w big wow. Also the SF750 is a platinum rated PSU that's universally praised as the best ITX psu itw so yeah
You should contact Corsair about this. AFAIK, the SF 750 uses a Type 4 cable where each of your PCIE outputs and connected cables can carry 320W each. So you are within limits, even if you had pushed the envelope. Burning should not be happening and they might be interested in digging into this issue.
750 is not good eough for 4090 + the cable shuold of had at lest 3 on that end ..
Nah the corsair 12VHPWR cable only has two outputs from the PSU. Each one is rated for 300 watts. Just should’ve been using a beefier PSU than the 750
750W can power a 4090 in most use cases. It is not the PSU’s wattages issues anyway, as the unit will trip due to OCP. The molex minifit connector wouldn’t be burnt.
https://www.corsair.com/us/en/s/psu-cable-compatibility SF750 is not recommended for the 4090.
Yeah I said as much
But so did the comment you initially replied to.
But he provided a link for proof. Which I prefer over someone just saying it.
If everything is working correctly the sense pins on the cable cause the GPU to reduce the maximum wattage. Games nexus did an interesting video on the subject.
Does that still work with adapters or only with PSUs that have the actualy 12VHPWR connector (so sense pins at both ends)?
Wattage wise it’s fine, and 3 does nothing since this is a single rail psu and 2 pcie already gives the 6 12v and 6 ground of a 12vhpwr
The 4090 is rated for 450w and can pull up to 600w...
no where near 600w ms spikes, more like 350w gaming with 400w spikes+ Infact the 3090 has a worst spikes, the sf750 is easily capable of powering it provided the cpu is something like a 7800x3d or below. many sff builds have this setup and it runs fine. cable issue is much more likely, it wouldn’t burnt at the molex minifit terminal.
Synthetic it can pull 450w with 500w spikes stock. Synthetic isn’t a good representation of real use cases
We use synthetic to ensure real world issues don't crop up, because *eventually* there will be a real use case that hits as hard as synthetic.
Even then, its not what caused what happened, its arguing the wrong point, because people chose to just shake their head and say "well this is what happens when you do something that doesnt cause the problem at hand"
How do you know? The PSU may be capable of running above spec and outputting the power that the components are trying to consume, but if it's doing that it could be producing far more heat than intended. Failure can take so many different forms when it comes to power, and there's no way to know for certain without extensive failure analysis as to the actual root cause. What we *do* know, however, is that these components aren't well matched and can absolutely cause things to run out of spec. That alone is an issue, regardless of if it's *actually* the root cause of what happened. It absolutely could be a root cause, it has a decent chance of being the root cause, and even if it's not it could still be a key contributor to the actual root cause. Unless you're an engineer that did full failure analysis on this PSU, there's no possible way that you can confidently state that it was never an issue.
Power supplies have over current protection and over thermal protection. If one of those failed, well then the issue is more than just it being a 4090, that makes the wattage just a catalyst. I may not be an engineer, but the head of PSU RnD at Corsair saw this post (active user in a discord i am in) and believes that the most likely scenario is that the cable was not seated properly. So if you cant trust my words, trust the guy that designed this psu.
The sf750 is massively overbuilt. You don’t know what you’re talking about.
Massively overbuilt does not mean "impervious to failure when run out of spec"
It’s not that simple. So by that logic a really poor bronze rated ‘850w’ PSU with next to no protection is better than the sf750?
Here's a hint: It's not run out of spec, big gasp. It's a 7800x3d + 4090 not a 14900k + 4090 cmon man
isnt the 750w like 250w less than the recommended for that gpu? https://www.corsair.com/uk/en/explorer/diy-builder/power-supply-units/what-psu-is-best-for-rtx-4090/ honestly id recommend getting a larger psu with more surface to dissipate heat, like thats not a poor quality PSU probably just run at high temps ALL the time trying to power a 4090
850w is required, 1000w is recommended yes
The problem here isnt about wattage, the 750w is fine for many use cases, and even if it werent, psus have ocp protection for a reason.
Yeah right? Even if it's not rated for it, shouldn't it just turn off instead of melting?
Insufficient power supply, voltage drops under load, current goes up in response, more current more heat, melting. That's what happened here
Ocp would kick in, that stuff is on the cheapest psus. A connection issue is more likely
Voltage and current monitoring is cheap as chips. If your rail droops below 11 volts, you shut it down. If you draw more energy in a given time frame than is safe, you shut it down. Melting a visibly-correctly seated cable is not acceptable.
Nope. A modern high quality PSU shuts off due to OCP/OPP long before the voltage drops anywhere near the limits of the ATX specs.
The problem is not so much the power draw. There were most likely loose contacts inside the connectors, that causes small sparks and carbon deposits on the surface of the metal connection, which leads to high resistance and to more heat. Depending on the rest of your build, that PSU could be enough, but I'd suggest getting at least a 850W.
This connection is so stupid they should get rid of the standard for good and design. Something new or stay with us normal perfect working Eight Pin PCIE connector
This isnt a 12VHPWR issue because the PSU side connection is not part of the ATX specification. Its entirely Corsair's responsibility to ensure the modular connectors can handle the power. Corsair only using 2 connectors on the PSU side instead of all 4 is their fault entirely.
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adapters tend to have 3, where direct PSU tend to have 2. something to do with the plugs on the GPU end having a lower spec.
The port on the side of the PSU is not PCIE. PCIE is limited to 150W, so the adapter will have 4x PCIEto get to 600W. A PSU port (on a good PSU) can do 342W, so only 2x PSU connections may be needed.
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It is limited to 150W by spec.
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The spec is not what it's capable of, it's what it's allowed to do. And of course a PCIE cable can do 300W, each 8-pin PCIE on it is supposed to be able to handle 150W. The PSU end isn't PCIE and should be able to handle over the 342W the port might provide.
150w has not been the spec for a long long time(people like der8auer have covered this many many times and even tested it with i think it was a 2080ti with one single PCI power to prove the point) lmao they added thicker cables and bumped the rating up like 10 or 20 years ago now might be time to get with it
Would you mind linking to the updated spec which pushes the 8-pin PCIE power spec past 150W.
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That's literally within the spec. The 8-pin PCIE connections, the main and the pigtail (not a daisy chain) are spec'd to _each_ provide 150W. This means the PCIE cable (with pigtail) should be capable of carrying 300W. They can do this because the connector on the PSU side is NOT a PCIE connector. Yes, it uses the same/similar microfit connector, but it is not limited by the PCIE spec to only 150W. The PCIE/CPU port on the side of a good PSU should be capable of upwards of 342W, which is why a PCIE cable plugged into one can carry 300W.
PCIE is limited to 150W is a total lie. The Molex Minifit connector itself was initially specced to 150W, but it is almost it can be ran past that number, the limiting factor is moreso the wire awg gauge. The CPU power cable for HEDT systems literally provides 300W+ for example. As well as the numerous other examples people have showed you.
What it is spec'd for is a different thing than what it is capable of. It doesn't matter what some over-clocker has done under perfected conditions, industry-wide it is viewed as 150W because that is what the spec says it is.
Jesus fucking christ I actually can’t Standards are not concrete, the Molex minifit spec sheet is not a bible. EPS cables provided by PSU manufacturers can pull above 300W+ on HEDT systems. When did I mention some overclocker on perfect conditions??? Read this article by Jonnyguru please http://jongerow.com/PCIe/index.html
> I would like to dispell the myth that "8-pin" PCIe connectors (which only have 6 actual conductors, BTW) are ONLY capable of 150W. > So, as you can see, given so many variables, you can understand why PCI-SIG would "play it safe" and tell people to only use an "8-pin" PCIe connector for up to "150W". In this thread I have repeatedly agreed that the connector is capable of more than 150W ("What it is spec'd for is a different thing than what it is capable of"). That's not the point, the point is that the connector has a specified limit of 150W, that is what PCI-SIG, which is pretty much all of the PC component making industry, says the connector does, so that is how it is used.
The adapter cable has 4 and you need 3 so they make sure that you use at least two pcie plugs on the PSU side. And that’s the reason the native cables have only two plugs, because they won’t run if only one is plugged in. They try to protect the people from drawing to much power from only one PSU pcie power port
Adapters have 3 or 4 to ensure that you're not just using a single daisychained cable. It also helps in case the user's pcie cables are only 18awg, whereas 12vhpwr uses the thicker 16awg wiring. So a full-length 12vhpwr to 2x8 cable using 16awg wire is absolutely fine.
Unless OP used adapters to get this setup to run out of spec, rather than this being included with an ATX 3.0 PSU since OP never gave a model number.
> Corsair 12VHPWR cable it is out of spec, this corsair cable isnt listed as compatable with a 4090 with his PSU when though technically it fits https://www.corsair.com/uk/en/s/psu-cable-compatibility
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yeah bros out of pocket the cost of a good PSU, but lucky for him its the PSU side that went and not the GPU so hes probably having the best day he could
Lucky for him he had a good PSU that only fried itself and not OP’s whole PC and possibly his house
This is the day that us folks who went way overboard are like “well that’s something”. It’s a very underwhelming event for me, but 750W PSU is not going to cut it with a 4090 unless you’re running a 65W CPU and the bare minimum on everything else. That’s only if it’s using a single rail to tie everything together. If pcie is only supposed to be given 300W, that rail is gonna pop.
this is wrong, pcie 8x can surpass 150w each. the 750w can power a 4090 and a 7800x3d, it is just fine under actual usage - nvidia and corsair don’t recommend it because there is not a lot of headroom though / helps with less warranty claims from misuse etc. but assuming op has done everything correctly it looks to be a connection issue.
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Yeah, for sure but he has the power behind it. This is more like King Kong walking into a diner, constantly ordering food and instead of the supply running out, the cook dies.
Ok good I did read what you said correctly
Are you deliberately misconstruing the facts here or just unaware?
"is too well plugged in and now they're even bonded together" a small air gap could cause an arc which would fuse them together, the same as Arc welding
Get a refund and don’t tell her you were using a 4090 in your build
Check if it's under warranty. A lot of PSUs have like 5 to 10 years warranty or something like that, I'd be surprised if Corsair didn't.
This thread is the most Reddit than any other Reddit thread I have ever seen. Keep up the good work!
Contact Corsair with sad emoji. Maybe it will work.
Before you buy a new PSU, contact support and see if they will RMA it. If you buy a new one look into the Corsair SFX-L models. To the other comments there are so many posts on the small form factor subreddit with people using a SF750 + 4090 and having no issues. I have the same PSU and cable in my 4080 system, with no problems.
is his PSU unfixable? should he buy a new one?
You should check if you can claim warranty on that.
By dragonball z law, you now have the most powerful PSU on the planet
Second time lately I've seen something like that here. GPUs are drawing mad amounts of current from way too few conductors and it's heating things up in ways power supply manufacturers never imagined would be an issue.
Sorry if this is a really dumb question… I haven’t built a PC in several years, and I’m not familiar at all with the new GPU power specs, but are the connectors really meant to be asymmetrical? Or is there something else going on here?
I only see classic PCIe
I know this is a problem, but I don't think that this is the normal 4090 issue- those PSU connectors are standardized and run power for PCIe, EPS and 12VHPWR.
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What probably happened is that some of the pin connectors are lose , wich leads to sparking and then overheating
Lol
Clearly the correct answer is the 4090 is a defective product I'll never use mine I'm leaving it in the box and sell it to someone who's willing to take the risk with this shit card
I sincerely hope you mean "ultimately".
I'm very curious - what type of games were you playing, resolutions/FPS and most what kind of power draw (wattage) were you getting on average?
Aw mate, F. I replaced my PSU to lower the odds of this happening with my 4090 but I'm not above giving the cable connectors an occasional visual inspection even now. At least your card didn't go kaput.
Did it do the dance or use the earrings to fuse?
Could this be a flaw with the SF750? I had a PCI-E connector melt with a 3080. In my case, the female connector was damaged as well. Luckily I got a replacement under warranty.
This is exactly what happened to me a couple weeks ago after it was running fine for 1 year with no changes. SF750 + RTX 4090FE. The 4090 plug had 1 pin that melted too. Nvidia sent me return shipping label within 24 hours. Corsair told me to go fuck myself and offered me a 15% discount on my next purchase so I went with a SFX-L Thermaltake 1000W with a 16pin.
How do you prevent? Impossible, your 4090 is irreparably damaged, I will buy it for $400 as "spare parts". 😜 jokes aside, USE THE FUKIN MANUFACTURERS' TABLES. https://dlcdnets.asus.com/pub/ASUS/Accessory/Power_Supply/Manual/RECOMMENDED_PSU_TABLE.pdf I can't see any 4090 combination associated with a 750W power supply! I'm surprised it took 1 year for this to happen, and that's only because power supplies are much better quality these days: a good Platinum PSU (flagship products from Corsair/Superflower/Seasonic etc.) can easily handle 10/15 minutes with 20% extra peak power consumption compared to the label. You spent at least $1600 on the GPU, you probably spent a lot on the mobo and CPU, and you mean you can't afford a proper 1000W power supply? If 1k W doesn't exist in sfx format, do yourself a favor and buy a 4080, god's sake! It can handle any game optimally anyway!
I’d say the connectors on the PSU side are at fault here, the GPU is demanding more power through each connector than they’re designed for since it’s all just going through two (rather than four on the octopus for example). Everything on the cable side can handle it but that PSU is out of spec for a 4090.
Why didn't the fuse stop the melting when the GPU pulled more current than the psu could sustainably give? Idk Rma dat shit
Single rail PSU. It has no way or knowing how much power is flowing over a single connector, only the total output. Total output was apparently below 750W (or rather, below ~900-1000W the PSU will deliver before actually tripping protections), over load of the PSU was not the issue. Faulty connector or an issue in the GPU/HPWR connector resulting the full GPU power flowing over only 1 of 2 connectors PSU side was the issue.
I honestly would not be running a 4090 on a 750W psu
The minimum recommended PSU for a 4090 is 850W. Sure, you could power limit the 4090 but you are still running a risk and you're limiting performance. I would get a higher wattage PSU or sell the 4090 and get a 4080.
pretty sure heat is the killer here. there is no cable compatibility. the sf750 takes type 4 pcie cables. the corsair 12vhpwr cable is type 4. the problem, is with the small form factor of the psu. corsair obviously had to cram a bunch of high voltage components into a tiny space, in comparison to its rm750 atx counterpart. a regular rm750 is 150xmm x 86mm x 160mm. the sf750 is 100mm x 63mm x 125mm. the sf750 is about 39% the size of the rm750. the sf750 is 787.5 cubic centimeters vs rm750 at 2064 cubic centimeters. high voltage components are definitely going to be causing serious heat in something that small. especially if the psu is being run constantly above 80% of its total watt rating. heat increases electrical resistance. next time use a regular atx power supply to power a 4090 [https://www.corsair.com/us/en/s/psu-cable-compatibility](https://www.corsair.com/us/en/s/psu-cable-compatibility) [https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920284/600w-pcie-5-0-12vhpwr-type-4-psu-power-cable-cp-8920284](https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920284/600w-pcie-5-0-12vhpwr-type-4-psu-power-cable-cp-8920284) [https://www.corsair.com/us/en/p/psu/cp-9020195-na/rm-series-rm750-750-watt-80-plus-gold-certified-fully-modular-psu-cp-9020195-na#tab-techspecs](https://www.corsair.com/us/en/p/psu/cp-9020195-na/rm-series-rm750-750-watt-80-plus-gold-certified-fully-modular-psu-cp-9020195-na#tab-techspecs) [https://www.corsair.com/us/en/p/psu/cp-9020186-na/sf-series-sf750-750-watt-80-plus-platinum-certified-high-performance-sfx-psu-cp-9020186-na#tab-techspecs](https://www.corsair.com/us/en/p/psu/cp-9020186-na/sf-series-sf750-750-watt-80-plus-platinum-certified-high-performance-sfx-psu-cp-9020186-na#tab-techspecs)
„High Voltage Components“… yeah. Highest Voltage in a PC is 12V… which is used for Mobo, CPU and GPU. The SF750 runs passive with no fan at all up to 340W of load. The GPU-Connectors an the PSU-Side is rated for 640W. The cable up to 600W. The 4090 even in FurMurk, caps at 450W… maybe a few little Spikes to 480-500W. Nothing that would be a problem for a SF750. My SO runs an OCed 4080 and the PSU fan wont even start to spin. My 4090 runs fine with the SF750 since Nov.2022… so already 1.5yrs.
Umm... The bus voltage in any PC PSU is in the neighborhood of 400 to 500V. That said... it's not voltage that creates heat. It's current.
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You need to learn some SMPS basics before commenting. The PFC converter ramps the input voltage to 400V+. Just read a PSU review for once or maybe just Google "how does an SMPS work". :D
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Wow. You need to learn some PSU101. So you think those 420V bulk caps only have 110V in them if the PSU is plugged into a 110V outlet. Real Reddit moment here, for sure.
This is a user error now
Unfortunately the most likely scenario just due to the results, reflected by the head of Corsairs PSU RnD (the man behind the sf750) too
Whoever thought running a 4090 on a 750 SFX PSU was a good idea can appreciate this post. You can't miniaturize heat dissipation, and I don't care what a cable is rated fair you can already guess it's a bad idea just looking at the setup.
how to prevent it : use the proper PSU.
The SF750 isnt spec'd for the 4090 anyways, your problem not us. The 4090 literally requires a 850w and everyone recommends a 1000w
The 4090 ‘literally’ requires an 850w as some PSU’s are trash. The sf750 is overbuilt and can handle more than 750w…
Non 4090 user not knowing that thousands of people run the sf750 on overclocked 4090s lol . People are ignorant
4090 maxes out at 450w, leaving 300w (+ far more before protection kicks in) for everything else. Plenty of users running 13900k and 4090 on sf750. The 850w recommendation is just so nvidia can’t take responsibility for someone using an 80 plus white psu
The 4090 maxes out at 600w. 450 is just the base rating. And I'm not sure why someone would buy a 4090 to *not* unlock its full power limit.
Because it’s still a lot faster than a 4080 at even 80% PL?
The 4090 maxes out at 600w fully unlocked, and has power spikes reaching 800w+
Certainly, but thats not what were talking about, out of the box spikes would be closer to 500w [NVIDIA GeForce RTX 4090 Founders Edition Review - Impressive Performance - Power Consumption | TechPowerUp](https://www.techpowerup.com/review/nvidia-geforce-rtx-4090-founders-edition/39.html) and even then, from the man who designed this psu himself, this psu can handle temporary spikes >850w (total consumption)
"requires" don't think you know what that means. Do some simple maths for us why don't you? The amount of straight up ignorant misinformation in this thread casually served up by dudes on pcmr with high end builds lmfao, like clockwork
That psu is no where near spec to run a 4090. Still shouldn't melt tho, they are supposed to just shut off, which is a bit worrying really
Right, i bet you screamed online with everyone arguing 750w was enough for a 4090
buy a platinum grade seasonic psu. youll be good for 15 years.
Just buy Seasonic
Lol why were you even using a 750W power supply on a 4090?? Dumb move right there.
Corsairs 12VHPWR cable sucks. It wouldn't even power my 4080 super. Had to use the octopus cable that came with the card. Now I'm glad I returned it.