[vanik]

Hi.
Ever since I moved to a new place a few days ago my computer has randomly been shutting off. I can sometimes reproduce it in certain situations (starting a game, for example), but as of late its getting worse and I can barely do anything after booting. After it shuts off, when you turn it back on everything seems to run but I don't get an output to my monitor and there aren't any beeps or anything. If you restart again though its back to semi-normal until it shuts down again. I thought this was the graphics card so I switched to a geforce fx 5600 (i was going to anyway after my old one burned out) from an old nvidia tnt.
The rest of the computer stats are:

athlon xp 2200
512M ram
asus a7v333 mobo
sblive audigy
generic network card
sony dvd-rw
400w power supply

in an antec case with about 5 fans..

i've reconnected everything a few times, taken out and looked at the power supply, and tried to wipe and install an operating system but i haven't been able to get it running long enough to do so..

from the similar questions i've read this might be a power supply problem... but any help is very appreciated.. i want to make sure thats what it is before i spring for a new psu