Rebuilding a new machine with a new L4S5M mainboard. Picked up a new 2.2 gig P4 chip for the processor and a new DURO 400W power supply. The machine will boot up, and it will go into bios fine or boot windows fine. The problem is, it likes to turn itself off. This could happen while I'm surfing in bios, or while it's booting in Windows. I've fiddled with the settings, but can't seem to find something that is stable. It's good for about 2 minutes before shutting off. If I try to immediately boot back up, it lasts about 30 seconds, and then progressively less. If I let it sit for a while, it will be good for about 2 minutes again, before shutting off.

What other equipment do you have attached to your machine (video card, sound card, etc), including the amount/type/brand of RAM? It could simply be a power drain.

Also, are you sure you've loaded all the latest drivers for your motherboard? (Double) Check on the manufacturer's website to make sure there haven't been any recent updates.