hmm I have a story to add:
well see, i had this crappy HP case that was designed for this old ATx form factor, it was running some old "super 7" type slot CPU (amd k6-2) i believe. so when i upgraded and put the socket A board into it, the power switch cables wouldnt connect correctly to the pin-block that controlled ATX led and switch activities, because it must have been some OEM piece of crap, or some outdated form factor.
SOOO i was turning it on and off with a screwdriver (*cry*... sigh this is so bad), by tapping the power switch pins.
anyways, one day i went down to turn it on, and it was kind of dark in that case I think, and all i remember was i touched some pins and there was a pretty big spark. i shudder to think what i actually shorted, but i have a feeling it WAS NOT the power switch +/-
I think the +3.3v lead runs through an area quite near there...
anyways after that, duron didn't work no more.