No output

Unplug the power
remove video card memory and cmos battery
reseat video card memory and cmos battery after a few minutes

see if it will post

if not fried mobo or vid card

thank you very much, but im not too well informed about computers. how would i take out the cmos battery?
the p.c. doesnt even beep when i turn it on, though i can hear the fan buzzing

The cmos batter is directly on the mother board it looks like a really big watch battery basically. You should be able to get a real small screwdriver and pop it out its only help in by a clip

Here's a checklist for troubleshooting boot problems:

http://www.tomshardware.com/forum/page-261145_31_100.ht...

I would guess you're having RAM issues if the system was crashing before. What are your complete system specs?