Turns out I had the last piece to replace was the faulty one after all: the PSU. It had acted up with extension cables before and in one way or another on my 5700XT, so it was the first one I suspected, ironically enough.
Thank you so much everyone. I had turned off my XMP without realizing it...
Thanks for the answers!
I mostly use it to offload games from my backlog and other downloads. It does seem to be failing and I'll be replacing it soon. I disconnected it entirely to see if the problem goes away, but it remains. My Pagefile appears to still be there.
Here's that screenshot...
This started happening again suddenly (more on the first time, shortly) where whenever I'm running a game or unigine benchmark my pc stutters nearly every second for a quarter of a second. It's as if those frames of information are just deleted. Additionally, my PC in general is slowed down...