My PC was damaged by rain entering through the top vents, and I've since replaced roughly 80–90% of the components. Despite that, it still crashes during games—usually going to a black screen, rebooting, and then showing a BSOD. It also sometimes powers itself on at unusual times, including during the night. I suspect the power supply may be failing and have ordered a replacement, but what symptoms would help confirm that diagnosis?
2 Answers
A common sign of a struggling PSU is the computer shutting down or restarting when the system is under heavy load, such as during a demanding game. A black screen followed by a reboot after several minutes of playing could fit that pattern, especially if it happens consistently in graphically intensive situations.
A faulty PSU can cause blue screens, but that’s less common than a complete shutdown or sudden restart. For a BSOD to be caused by the PSU, the voltage usually has to dip enough to make a component malfunction without dropping far enough to immediately switch the whole system off. Since the machine suffered liquid damage, other damaged or corroded components could also be responsible.
Before assuming the replacement PSU solves everything, check the Windows crash dump files in C:WindowsMinidump. Those logs may identify whether a driver or particular component is causing the blue screens.

That matches what I’m seeing. It usually happens after about ten minutes of running a game at 4K, followed by a black screen, reboot, and then a blue-screen error.