Hello everyone. Slightly long story

Several months ago I started having an issue where my computer would randomly freeze and do this:

(Both the problem and the specs of my computer are in this gallery in addition to my typical temps. Keep in mind that my main monitor, which is connected to my GPU freezes along with the computer while the secondary monitor is connected to my motherboard and will shoot black and white and purple bars up and down the screen indefinitely.)

https://imgur.com/gallery/oRcPP

I have tried seating and reseating my gpu, RAM, CPU with new thermal paste, turning my PSU down to face toward the exhaust instead of up. The GPU has new thermal pads. I even reinstalled the motherboard, updated the BIOS, made sure my GPU is on stock settings, ran a memtest, dusted the inside of the computer. Removed the GPU and just kept my monitors connected to the motherboard to work off the iGPU. Still would do the same except both computer screens would do red and black bars instead.

When I originally did all of this months ago, the problem seemingly went away for good. Now, in the past week it is back for no reason. I can't time it. It can go hours without doing it or last only minutes before it kicks in. I can play super heavy gaming on it for hours and nothing happens while only a few minutes of regular use can send the comp into a tailspin. And vice versa. It is completely random. I'm wit's end and Googling the problem has come up with zero results.

When this problem happens and I do a reboot, it often refuses to come back on unless I leave the computer for hours and come back and turn it on again.

Please help me. I feel ready to give up on custom PCs forever.