With my level of knowledge - I would say it is often difficult to pinpoint what is causing problems like this and you need spares of components to swap out to try and resolve them.
If you have cleaned out the pc, resat the processor, updated drivers, increased your cooling, checked your cpu cooler, a couple of full virus scans, you are not left with much to try other than trying a different processor, motherboard, power supply, reinstalling your Operating System
You can always just run the pc with the side panels off and replace something when or if it blows rather than spend time and $ trying to get to the root of the issue.
I have built a lot of gaming PCs for myself over the last 15 years or so and once in a while I have been stumped with what has been causing an issue and ended up being lucky guessing it was a power supply or replacing a motherboard, CPU etc.