I recently fitted 2gb of RAM to a very old computer and this was working fine until a few days ago. I leave my computer on sometimes for days on end. My girlfriend came to use it while i was out and said it had frozen, she then switched it off at the wall and it hasnt come back on since. There is still a little green light on the front but none of the fans are working. I took the cover back off and noticed a red LED light on the motherboard and this is on when the power is on too. I did notice that the fan starts for a fraction of a second and then stops. No other sounds or lights, nothing, just the red LED on the board and the green LED on the front. Any ideas, anyone please?x:confused:

Sounds like a faulty Power Supply Unit (PSU).
Swap the PSU for a known working unit of similar specifications.

try reconnecting all power leads and unplug your PC and shut the switch off for 2 minutes before starting and then recheck PSU for fault (as it doesn't start).......then try another PSu and see if it fixes the prob..................