Overclocked my CPU once...
It was an AMD Athlon XP 2100+ with the standard AMD Cooler. I pushed it to 2,1 Ghz.
It runned stable for about one evening. When I turned my computer on next morning the screen went black.
After examination of the CPU a chip of the core broke off, so now I've got an AMD Athlon XP 3000+ running like a dream. No OC'ing anymore here!