Yesterday, I opened my case up to check something while the computer was still on - stupid, I know - and dislodged something, causing it to shut down.
After some fiddling, it seems that:
1. The computer will boot up without the GPU. I have no onboard graphics or a replacement GPU on hand, however, so I don't know how far it gets.
2. The computer will boot up with the GPU plugged into the PSU, but not in the PCIE slot. Again, can't see how far it gets.
3. The computer will not boot up with the GPU in the PCIE slot, whether or not it is plugged into the PSU. Rather, the system and GPU fan spin up, there is a click, and then nothing else happens.
I've used an eraser and isopropyl alcohol to clean the GPU contacts, to no avail. In addition, I've reset the CMOS. Just from the above, it seems like I've killed the GPU, and I've ordered a replacement so that I can confirm.
In the meantime, however, I'd appreciate it if anyone had any other suggestions. Is it possible that the PCIE slot itself is damaged? How commonly does that happen?