Computer becomes unresponsive and blacks screens

Oct 30, 2018
Alright so, I'll give a bit of back story to my issue first:
I am an avid gamer and so one day I was happily playing Overwatch and after a couple of hours of happily gaming, my monitor turns green and everything become unresponsive - however my pc and fans are still running. I force shutdown my pc - by holding down the power button - and boot it up again, and after a couple of minutes the same issue occurs - but this time with a black screen. At first, it seemingly happened at random intervals - as sometimes it would happen even before the windows login screen but sometimes it would happen 10 minutes after I've launched a game.

In attempt to fix the issue, I have tried removing the graphics card, which helped. It hadn't shut down since. Because of this, I assumed that my graphics card had overheated and broken. I tried replacing the thermal paste in the gpu but that didn't help either. Therefore, I bought a new GPU and, to my disappointment, the issue is still occuring.

Something strange to note, is that, with my new GPU installed, it happens the moment that I try to launch a game - or the pc seems to want to use the gpu...

Furthermore, I find it important to add that, when in Windows Safe Mode, and I attempt to launch a game, instead of becoming unresponsive, the game just closed without an error message or anything - no black screen and I don't have to shut my pc down.

This situation is really getting on top of me and I would be truly grateful to anyone with a potential solution.

EDIT: forgot specs

CPU: i5-4690k
RAM: Crucial Ballistix Sport 16GB (2x8)
Motherboard: MSI z97 pc mate
SSD: Samsung 860 Evo 250GB
HDD: Western Digital Blue 1TB
GPU (originally): R9 380 4GB
GPU: RX 580 4GB
PSU: EVGA Supernova G2 650w 80+ Gold