My computer RANDOMLY stopped turning on.
I discovered it works when jumped, but not when the cpu cable is plugged into the motherboard.
I tried a different PSU and it didn't change.
Is this my motherboard? CPU? Something else?
Already bought new psu for no reason so I want to be sure before I purchase something else.Hi Stackers,

First what other specs can you give on the computer. A quick way to do this is if you post some pictures of the power supply label and motherboard etc.
Then we will know what advice to give
Thanks I should say this computer has worked for 5 years, so I'm pretty sure somethings just dead, not incompatible.

what i know
-GIGABYTE GTX 770
-asus motherboard
-corsair cs750 power supply
-forget the CPU because it's under a massive heat sinkThanks for the info

I WOULD visually check for anything AROUND the CPU on the motherboard that looks like it has been hot.
With the power disconnected and the cpu power plug disconnected from the motherboard using a multi meter on the ohms range check between the negative and positive pins  of the cpu power socket it should be mega ohms. On a diode test it will be about 400mv or higher if it shows as a short then the motherboard is faulty.

If you don't fell confident doing this, then find a tech to do it.
Wait. The power button has gone bad.
Cut the wire pair that goes to the button and replace it with a push button.
(The only one I found says RESET, but that don't matter.)