My PC won't stay on for more than 3 seconds before it shuts itself down and reboots itself about 10 seconds later. As long as the PC is plugged into the wall, it will continue to do this.

I thought it could've been the power supply, but I replaced it and nothing changed. It won't even let me start up in safe mode (Windows XP) and I can't start the PC up manually.

I had my specs written down, but I can't find the papers right now.
I just know that it had a lot of memory and a lot of hard drive space. A very good video and graphics card, and EVGA mobo.

Can anyone help me?

-TNC

Heya,

Tried resetting BIOS?

Check all the heatsinks, if one became dislodged, then it could cause parts to overheat and restart, i read somewhere on the net that a guy's northbridge heatsink wasnt on right, and his pc refused to stay on, until he figured it out about a week later

EDIT: to reset the BIOS as darklord suggested, go into the cmos options and hit restore fail safe defaults, or a similar option, if you cant get this far, unplug the pc, open it up, find the clock battery, take it out and short the 2 battery connectors for about 5 secs, re-insert the battery, plug it baack in and turn it on, or your motherboard may have a bios reset jumper, normally near the battery, in which case turn off the power, open it up, find jumper, and short the 2 pins, and if in doubt short all the jumpers, the pc is off so it wont do any harm

I reset/cleared/short the CMOS RAM pins and there was no change.

Could it possibly be just a short in the power switch or something?

-TNC

Checked that all cables are plugged in firmly?

Sounds like you have to do some physical troubleshooting to me. If the computer doesn't stay on long enough to get into the BIOS, then remove everything (all devices, cards, memory, keyboard) from the motherboard except the monitor and video card (if it's not built in). If it still doesn't work, it's likely the motherboard.