Like I said in the title - my computer had been freezing during games/rendering, and a couple of times doing other things like surfing the web. I started noticing that if I started playing a game fresh after booting, my PC wouldn't freeze for the 5 or so hours I was playing that specific game. If however, I were to close that game and launch another game, or any other demanding software, my pc would freeze within 15 minutes. The same goes with if I were to boot my computer and leave it idle/use chrome for about 15-20 minutes - it will definitely lock up within minutes of launching a game.
I've reformatted my computer since and the problem still persists.