The other night, I was playing a game on my desktop PC when the graphics started stuttering and, eventually without warning, the entire display froze and the speakers emitted a constant buzzing sound. Windows wasn't even able to display a BSOD — the system simply froze with garbage on the display and buzzing on the speakers.
I powered down my PC, then tried turning it back on. This time, it wouldn't enter POST; the display remained in power-saving mode while the fans and disks started spinning as usual. I tried this a couple more times, but no dice.
So I decided to call it a night and figure out what to do about my PC the next day. Except in the morning, when I tried turning it on again... it POSTed successfully and booted to the desktop. Everything was working normally again. Apparently, the hardware (I'm assuming it's the motherboard specifically) got knocked out, but recovered overnight.
I'm about to get a new rig anyway, but why would my computer simply stop POSTing — and only for a few hours — after a really bad crash, then suddenly start working normally again without me doing anything special about it? How would I go about troubleshooting this whole situation post-mortem?