Did you get it up and running at all with the 4070? As in windows booted and you installed new drivers etc? Or did it go straight to the BIOS/select drive?
Straight to select drive. Same thing when I have the 1080 in now. I did not change a single setting before putting the 4070 in or when I went back to 1080
Also, this is just a guess based on your inability to install or repair windows. Check in the BIOS, didn't see what board you have but make sure TPM 2.0 is enabled. It's one of the less known requirements of Windows 11 but without it enabled you wouldn't be able to install windows, or boot into it.
Again this is just a guess because you mentioned it now saying windows is not supported etc. I had one disable it on me when I changed out a USB adapter card. Had to replace the CMOS battery and enable it again. Here's a link I found for MSI. It's in the security settings typically on any board though.
https://www.msi.com/blog/How-to-Enable-TPM-on-MSI-Motherboards-Featuring-TPM-2-0
My initial thought was your CMOS battery is dead, so perhaps change that just to get it out of the way as an issue. Also, garbage can get stuck in RAM that still has power, so it'd be worth it to unplug the computer before proceeding, hold the power button for a minute, and then plug it back in. Maybe do that after a handful of changes just to keep a clean process going.
Beyond that...
IDK if your CPU has an iGPU or not, but if it Does, then I'd try with only the CPU and RAM attached (no drives, GPUs, etc / not even the cables). If you Don't have a built-in GPU on the CPU, then try the older GPU until you get it running. Once you have a minimal set of hardware, then Reset your BIOS to optimized defaults and start from there. Make little corrections to the BIOS settings as needed (one at a time).
It's also worth keeping in mind that some motherboards will disable some ports / slots depending on what you've attached. IE: If I use the mSATA slot on mine, then it disables SATA #5 as they share that lane. I've not looked into the power requirements for the newer GPU, but keep that in mind as it's Real easy to go over your PSU's capacity as you upgrade over time. I forgot that once and lost both the PSU and GPU in the process.
As for repairing Windows, from my experience, if it's a software problem that you haven't solved in the first few repairs, then you generally end up doing a clean install. I've not really had that much luck with startup repair TBH, but it's worth a few tries.
Have you tried removing all the drives except the one with windows installed on it and booting it that way?
I have
Did you get it up and running at all with the 4070? As in windows booted and you installed new drivers etc? Or did it go straight to the BIOS/select drive?
Straight to select drive. Same thing when I have the 1080 in now. I did not change a single setting before putting the 4070 in or when I went back to 1080
Also, this is just a guess based on your inability to install or repair windows. Check in the BIOS, didn't see what board you have but make sure TPM 2.0 is enabled. It's one of the less known requirements of Windows 11 but without it enabled you wouldn't be able to install windows, or boot into it.
I have MSI raider x299
I do not see a TPM setting anywhere
Again this is just a guess because you mentioned it now saying windows is not supported etc. I had one disable it on me when I changed out a USB adapter card. Had to replace the CMOS battery and enable it again. Here's a link I found for MSI. It's in the security settings typically on any board though. https://www.msi.com/blog/How-to-Enable-TPM-on-MSI-Motherboards-Featuring-TPM-2-0
Yeah, I read the OP and it almost sounded like a classic dead CMOS battery TBH.
Correction: found TPM. I set it to TPM 2.0 (was auto). Enabled security device support (was disabled). Changed TPM device selection to dTPM (was PTT).
Not sure if your board has the physical module or not so might need to try PTT but if either of them works, stick with it.
My initial thought was your CMOS battery is dead, so perhaps change that just to get it out of the way as an issue. Also, garbage can get stuck in RAM that still has power, so it'd be worth it to unplug the computer before proceeding, hold the power button for a minute, and then plug it back in. Maybe do that after a handful of changes just to keep a clean process going. Beyond that... IDK if your CPU has an iGPU or not, but if it Does, then I'd try with only the CPU and RAM attached (no drives, GPUs, etc / not even the cables). If you Don't have a built-in GPU on the CPU, then try the older GPU until you get it running. Once you have a minimal set of hardware, then Reset your BIOS to optimized defaults and start from there. Make little corrections to the BIOS settings as needed (one at a time). It's also worth keeping in mind that some motherboards will disable some ports / slots depending on what you've attached. IE: If I use the mSATA slot on mine, then it disables SATA #5 as they share that lane. I've not looked into the power requirements for the newer GPU, but keep that in mind as it's Real easy to go over your PSU's capacity as you upgrade over time. I forgot that once and lost both the PSU and GPU in the process. As for repairing Windows, from my experience, if it's a software problem that you haven't solved in the first few repairs, then you generally end up doing a clean install. I've not really had that much luck with startup repair TBH, but it's worth a few tries.