Re-install Windows: Check
Everything to stock settings, install the necessary programs to test your HDDs, Video Card, CPU and RAM.
Run all said programs.
If all good, check them all off.
That still leaves...PSU, loose wires/maybe a screw came out and is shorting the motherboard every so often, etc.
I think it's your CPU, either unstable overclock or it's overheating/or something on the motherboard is overheating.
I have the same CPU, I try not to let it get above 75c.