I just built this computer.. Core 2 DuoE8400 Gigabyte g4m1-ES2L 4 gb Kingston pc6400 EVGA Geforce 9800 GT 1gb ram psu 550 watts This problem is odd and I am having a very difficult time pinpointing the culprit. It seems, after leaving my computer powered off for about two hours it has a very difficult time powering on. Sometimes it will power on for a few seconds w/o displaying any video and then abruptly shut itself off but mostly it will just shut off immediately after power on. After attempting to power it on a few times it will eventually boot up, and, once booted, I can restart it multiple times without incident. I have found, however, that if I play a game it will usually provoke a shutdown which leads me to believe theres something wrong with the psu. The psu and case were super cheap and I got both of them for 40 bucks so I really hope this is the problem and not a bad motherboard. Update: Ive opened it, and It looks like the cpu fan will occasionally not work on power-on. This is what is causing it to shutdown abruptly at start-up. I'm not sure if this is the PSU causing this or a bad cpu fan.

it sounds like to the psu to me, had the same sorta problem myself. you've proved it can not be a overheating problem so that leaves psu. Chez

Those are all problems I would check first then I would check the motherboard for any damage as that was what was wrong with mine

Replace the fan! "Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10

I hope its just the PSU, I took this PC Assembly course and learned that one of the reasons why PC tends to shut down is in the manner how you installed the CPU, if it's not correctly installed then eventually PC shuts down to avoid overheating. Try removing/installing the CPU again...

I didnt even install the cpu to begin with. I paid Frys 10 bucks to install the heatsink/cpu into it. If it took me having to reinstall the whole cpu. I would just return the whole damn thing, but I am going to put a new power supply in it and see if that fixes the problem.