I've had some very occasional crashes with my PC a self-built Intel i7 system. These happened in both Linux and Windows, suggesting that it was a hardware issue. I checked and regularly saw temperatures in excess of 80 degrees C, which apparently is way too hot. When it occasionally gets even higher the CPU shuts down to prevent damage. Sensible, but annoying.
So recently I took the plunge* into water cooling with the simple, self-contained H60 system from Corsair.