PC turns on fine, starts choking at random, then doesn't display anything on restart

EDIT: the other day I tried replacing my CPU with one I found out didn't fit, and then I placed the old CPU back in its place and it worked fine for the next 3 days. I'm wondering if this is a problem with bent pins on the motherboard.

I started having this problem a couple days ago, right after I'd already had fixed a previous motherboard problem where the PC would immediately turn off when launching.

This morning, I turned on the computer and it was working absolutely fine. I was playing a game with YouTube in the background, and then the PC would start "choking" at random. There would be random lag spikes like in a video game, except it was happening across the entire computer, even distorting the YouTube image. At a previous instance where this happened, the computer would immediately restart itself. So to prevent that, I'd shut down the computer to manually restart and not lose any progress. Then, I'd try to turn the PC on again, and everything seemed to work and my Bluetooth speaker connected to the computer, but the screen wouldn't display anything. The monitor didn't show it was disconnected, it just idled in power save mode.

I've never seen this happen and I'm hoping someone has an explanation or experience with this.