Question PC doesn't turn on. Troubleshooting leads to gpu BURNING. Could you help find the issue?


May 8, 2014
I posted here since this seems to concern many components.

mobo: Asus z87m-plus
cpu: i5 4670k
gpu: EVGA gtx 970
psu: Mine: Corsair cx750 / Friend's: Coolermaster MWE 550

One day I click power button - PC doesn't turn on. There has been no event or a component change, the issues started out of nowhere.
PSU first suspect. I disconnect everything and I short pins 4 and 5 to see if the PSU works. It does. It can even run an external fan.
Then I connect PSU, mobo, cpu and ram. The PC boots into the BIOS sucessfully.
Next, I connect all drives and GPU. PC refuses to boot. My next thought is: PSU has lost power to run the GPU somehow.

I borrow a PSU from a friend. I test it and it also refuses to boot with GPU on. Booting without GPU, the computer gives me "Press F1 to start setup". I press F1 but nothing happens.
I reset cmos through the pins on the mobo and change the battery. I boot the PC without the gpu, it doesn't get stuck on Press F1, it loads into BIOS. Then I boot into windows, it all seems good.
Now I put the GPU in and press the power button. PC doesn't stop, it start running. GPU catches fire??? I shut the PC down.

What now? Could the mobo be damaged? If I put my gtx770 in, will it also burn? Why did the two PSUs refuse to boot with the gpu on, but after I changed cmos battery, it didn't prevent the dangerous boot. Can a mobo even detect too high current into the gpu, doesn't most of the power come from the pins, not the PCI-E?

Thanks for reading.
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