So I was using my computer fine last night. I cut it off and went to bed. I then woke up this morning and every time I tried booting the computer it would get right past the windows loading screen and then restart. I have tried two harddrives and both times it does the same thing. I also have tried to use the windows disk to reformat the harddrive and the computer restarts itself also.What could be the problem?

Specs if you need them
Asus SK8V
AMD FX-51
6800Ultra
3gb Ram
470w Power Supply

Will it allow you to boot into safe mode?

Nope

Okay, so you replaced the hard drive? and you weren't able to format it? Is that correct?

Could be any number things. You say you have 3 gig of ram? Try booting with 1 gig, or 2 gig, ie, removing one of the chips. Clear the BIOS (there'll be a jumper to do this). Can you get into BIOS? If so, select "Load Optimized Defaults". Failing all this, could be a fooked motherboard.

Yes that is correct

Also I'll try what you said Tony.