my computer is 4 years old. im trying to determine if its hardware or software issues. My computer powers up, loads up to the screen where i can select bios. as soon as it attempts to go to bios the computer shuts off. after that it will only stay on for 5 or 6 seconds then shut off. power supply, ram, hard drive have been tested on other comp and works fine. all thats left is motherboard or cpu. cpu fan powers up. what could this be. is it hardware or possibly a virus? Windows xp, mother board=Asus P5N-E SLI nForce 650i SLI Socket 775 1066MHz DDR2-800, cpu= intel 6600
Since it is all happening before the OS loads, that tends to rule out software. My initial thought here is that the CPU is overheating and you're triggering a thermal cutout with the subsequent boots, however without the unit in front of me to poke and prod, it'd be difficult to say for sure.
A good first step is to break the unit down to just the bare minimum needed for POST. If you still get the same problem, you've at least limited the number of components that need to be tested. It also couldn't hurt to scrape off the old thermal grease on the CPU and apply some fresh grease, assuming you haven't done that in the 4 years you've owned the system.