Question Computer suddenly turned off and won't turn back on with CPU cable inserted

[ItsMeBobou]

So my computer turned itself off and wouldn't turn back on so i went ahead and bought another PSU to rule out if the fault was in the PSU, Both with new and old PSU the computer doesn't boot if CPU 8 pin cable is in, starts normally if only the 24 pin is in. I guess the fault lies in the motherboard? There's really no visible damage on the board itself either or the sockets. Any help is appreciated! In terms of what i should try replacing i guess the motherboard is up next?

is the issue with the motherboard or the cpu and is it fixable?


Motherboard: Asrock FX990 Extreme 3
old PSU: Corsair CX850M
new PSU: Corsair RM750x 80 plus gold

 

[Flayed]

I dunno I guess if it works without the extra power cable just leave it unplugged?

 

[Mr.Spock]

try reloading default/optimized settings in bios?
maybe there' was glitch and a bios setting was corrupted

So my computer turned itself off and wouldn't turn back on so i went ahead and bought another PSU to rule out if the fault was in the PSU, Both with new and old PSU the computer doesn't boot if CPU 8 pin cable is in, starts normally if only the 24 pin is in. I guess the fault lies in the motherboard? There's really no visible damage on the board itself either or the sockets. Any help is appreciated! In terms of what i should try replacing i guess the motherboard is up next?

is the issue with the motherboard or the cpu and is it fixable?


Motherboard: Asrock FX990 Extreme 3
old PSU: Corsair CX850M
new PSU: Corsair RM750x 80 plus gold