My in-laws PC, which I built for them, has recently started to shut down on it's own. They also claim that sometimes it will not boot up. I have it back at my house, and it seems to be running fine. I let it run overnight, ran it through some benchmarks to stress it, and it seemed fine.

I see in the Event Viewer, under system, there are a number of critical errors relating to unexpected shut downs. My question is this. If the system shut off due to excessive heat, would that trigger a specific error in the Event Viewer, or would it just give the unexpected shutdown error?