Why Does My PC Keep Crashing Randomly?

I've been having a strange problem with my PC that's hard to explain. It's sitting on top of a drawer, and when I close the drawer a bit too hard, my screen goes black, the fans spin like crazy, and the whole system freezes. The only fix is to use a toothpick or something similar to hit the reset button on the case, since it's recessed.

Even more oddly, my PC crashes randomly while I'm using it. If I'm just on the desktop, there's a 10% chance of a crash. Running a lighter game like *RimWorld* bumps that up to about 50%, and with something like *Red Dead Redemption 2*, it's around 80%. Interestingly, these crashes happen more often in the morning and decrease as the day goes on. After a reboot, I seem to be able to play without issues for longer stretches.

This started happening while I was playing *Muck*. My graphics card is an RTX 3060, and when the crashes occur, the lights on the GPU turn off, leading me to suspect either the GPU or the power supply unit (PSU) could be at fault. One more weird thing: after trying to reset the system several times out of frustration with *Arma 3*, I got a "memory overclock fail" error on reboot after messing with the DisplayPort cable.

Here's my setup:
CPU: 12th gen Intel Core i7-12700f
GPU: RTX 3060 12GB VRAM
RAM: 32GB
Storage: 2TB (1.49TB HDD, 231GB SSD)
Case: Genesis IRID 505 ARGB ATX Gaming Case
PSU: Unknown, but it's a prebuilt system and I've heard they tend to use cheap power supplies.