My computer has been randomly restarting for about two weeks now. I can be doing anything on it, and it will restart for no apparent reason. After restart it seems to have trouble booting back up. The power button on the front of the case usually starts flickering sporadically, and I have to hit the switch on the power supply to turn it off, and then give the computer a good thump and it seems to start working again, usually for a few more hours before it starts all over again. I'm thinking it might be the psu, but I'm not ruling out the motherboard or cpu. I was just hoping to get input from others on what they think it might be before I go and spend money.
I've checked all connections, and gave everything a thorough cleaning with air. And I'm pretty sure it's not over heating, I've been running motherboard monitor and the CPU never get's over 35 celsius even under load, and the motherboard seems to stay right at 25 celsius at all times
Win XP pro
P4 2.8ghz 800mhz fsb
1 gig PC3200 running dual channel
ATI Radeon 9600xt 256mb
Gigabyte GA-8IPE1000 Pro-G motherboard
Allied ALB-500w PSU