Actually I think I discovered that the problem was still graphics driver corruption. When I reinstalled it the first time, I just installed it on top of the previous drivers which did nothing, and I was also getting graphics driver crashes on the desktop.
I used driver sweeper to remove every single Nvidia driver, and then on restart my monitor quickly went black with 'no input detected' :x
So I reinstalled the drivers after they were fully removed in safe mode, restarted and it works again, and I managed to run 3 loops of heaven benchmark without any problems. Im fully testing my CPU + Ram again at their previous max overclocks to make sure everythings fully stable, and then I'll try the game again after a while.