Drivers/Hardware :: Can't Diagnose Cause Of Display Driver Crashes And PC Restarts

Been having a hard time diagnosing the root of the issue I've been having with my custom-built PC. Two weeks ago, I started getting display driver crashes every time I was in a game. It would crash, then recover. This continued for a few days. I shrugged it off because I am aware that NVIDIA drivers have been having issues with Windows 10 lately. They are prone to crashing. However, a few days later and continued sporadic display driver crashes in-game I had my PC completely restart and then nothing happened. The monitor was blank. The LED's on my fans were on. I tried to power down the PC via shut down. Nothing happened. I had to shut it down by flicking the PSU power switch off. I then flicked the power back on, pressed the power button on my PC...same thing. LED's on fans were on, but the PC wouldn't boot. I opened up my side panel and saw that the CPU fan was not spinning. I powered everything down. I proceeded to take out the CPU 4-pin connector and use the other one (it was originally an 8-pin). The PC then powered on and has been working perfectly until today.

While in-game I had around my display driver crash and recover 5 consecutive times within seconds of the other. Eventually I turned the game off. My PC was normal until maybe an hour or two later I tried to launch another game. This caused my PC to instantly restart after getting past the main menu and loading a save game.

I proceeded to shut down. Used the original 4-pin when this happened the first time. It booted up, so it obviously wasn't a bad connector. Same thing. Tried a different PCI-E connector. Same thing. Then I proceeded to reseat my GPU, RAM, CPU, GPU and mobo power connectors. Well, I am now booted back up, launched Witcher 3 and no crash. Was in it over 10 minutes until I turned it off.

I was moving my PC around the week prior to the first time all this happened. I am wondering if my GPU simply got loose? My mobo doesn't have those things that snap into place, as you would on RAM slots. I also upgraded my RAM at the beginning of September.

Maybe I need a new PSU. Maybe I need a new mobo.

PC specs are as follows:

CPU: Intel i5-4590 3.3GHz;
CPU Cooler: Stock Intel;
Mobo: ASRock H81M-HDS Micro ATX LGA1150
GPU: EVGA GTX 960 2GB SuperSC ACX 2.0+
PSU: Corsair CX750;
RAM: Corsair Vengeance 16GB 1600MHz;
HDD: Toshiba 2TB 7200RPM;
Keyboard and Mouse: Corsair K70 Cherry MX Red Keyboard + Corsair M65 RGB Mouse

Temps are all normal. I know the CX line of Corsair PSU's isn't the best. I've had this since around July (around the time I got my GPU) and I don't have coil whine. I don't plan on keeping this PSU forever, I do plan to get a better one but at the moment this is what I have. I DID have coil whine or some sort of sounds when my display drivers were crashing soon as I launched a game. But again, since I reseated my GPU, RAM, etc, it appears to be stable and launching a game no longer restarted my system.