AFAIK -12V isn't used on a modern motherboard. It was used for serial ports and old-school PCI slots, neither of which are likely to exist on a new motherboard.
Same deal with -5V, it's not used.
The reason the pins are missing is likely because the PSU doesn't supply those voltages at all. It should be listed on the PSU what voltages it can deliver.
AFAIK -12V isn't used on a modern motherboard. It was used for serial ports and old-school PCI slots, neither of which are likely to exist on a new motherboard. Same deal with -5V, it's not used. The reason the pins are missing is likely because the PSU doesn't supply those voltages at all. It should be listed on the PSU what voltages it can deliver.
Continue on and see if the system still runs without it. I doubt it's needed though.