PC is restarting when playing video games

[dermonosmemes]

I have been having computer issues for a while now. My PC restarts while playing video games. The issue used to be fixed for most games by enabling V-Sync but now this method is mostly ineffective. My PC also restarted during a PSU test, which I have a video of below. It cannot be a GPU-related issue because I switched out my old 770 for a new 1080. My PSU is a Corsair 850 W Silver, but it has some age on it.

Thanks,

Footage of the PSU test: https://imgur.com/NR9Da5i

 

[Saturnity]

BSOD? Whats your processor

 

[dermonosmemes]

BSOD? Whats your processor

Nope, no BSOD. My computer just restarts when I'm playing video games. It's as if I press the restart button. Processor is i7 4790k. I've applied thermal paste to it, but the problem persists.