Hi all, I'm having trouble with a friends PC that I offered to have a look at. All I was going to do was speed his machine up a bit as he complained that it was running extremly slowly. i.e 6 mins to load windows! Checked to find that he only had 128 MB of RAM installed. So found some old PC133 RAM that I had lying around and booted it up... Loaded window in just over a minute and all was looking good....then. Heard a noise from inside the PC and it just powered off (not shutdown) Opened the case to find that one of the plastic clips on the retainer bracket for the heatsink fan had snapped off. Purchased a like for like bracket and replaced it. Power it up but nothying happened, apart from a slight movement from the CPU fan. (half a turn if that) So thought it might be the power supply so purchased like for like again and replaced part. Powered it up and the same thing, just a slight movement from the CPU fan. So thought it might be the processer, replaced processer with a spare 1.7MHZ celeron, thermal paste etc, remounted heatsink and powered up. And It worked, went through POST and into loading OS!!!!!!!!! YAY I thought to myself, thank god for that. It loaded up desktop and then after about 20 secs, returned to it's initial problem and just died again!!!!!!! Now when I power it up, the CPU fan spins as do HDD but doesn't perform POST, no BIOS screen or memory check, no output to display etc... So now I'm thinking has something blown up again!! Checked to make sure the system board wasn't making contact with the case and it's not so hopefully componets are all still O.K. I'm guessing that it could be an overheating problem and that the System board just shut down to protect the parts but since the PC does nothing now I have no way of checking. If the memory wasn't compatable witht he board then it wouldn't have booted in the first place. The power supply is new and I've tested it in my machine and it works fine. The CPU must work as the 1st time it performed the POST with no error beeps. Does anybody know what could be causing the problem as I'm fresh out of ideas? This was supposed to be a simple upgrade for a mate and now it's starting cost me alot of money and time and can't afford to buy any more parts and said I didn't want any money off him untill his PC was returned working. (thinking a simple swapping of memory modules would do the trick. PLEASE if anyone has any ideas could you let me know as I've tried everything I can think of and I'm starting to lose my patience with it. Thanks for reading. Help me O B 1 kenobi, you're my only hope.