I had a problem kinda like that. I would turn in the pc it would run for like 2 or 3 secs and then turn off. I thought I had some bad ram. So I RMA'd the memory and got the new stuff in and it did the same thing. So I took the cpu off and pull the cpu out and put it all back in. Well when I put it in this time I plugged the hsf fan to a different spot and boom it all works now. It really pissed me off cause I went without my pc for like 1 week.