what is wrong!?

Ok, so I recently bought a new computer that I assembled earlier today. But when I went to install windows, everytime that I hit enter to get into the setup, I got the same error which was something like "IRQL_NOT_LESS_OR_EQUAL". Sometimes I would hit enter and it wouldn't do that and it would just go to the next screen and freeze, then just reboot randomly. So my friend had an extra harddrive with windows already installed on it and he brought it over and we plugged it in. Everything seemed to work except that after windows would show the loading screen and right before the login screen popped up, it would reboot and would just continue in a reboot cycle.

We think it may be a faulty motherboard... anyone know what is wrong for sure?

Last time i had that error its was a bad stick of ram. once i replaced it it never came back up. if you have 2 sticks remove one and go back to what your doing and if it happen again remove the other and replace the one u took out.

So my friend had an extra harddrive with windows already installed on it and he brought it over and we plugged it in. Everything seemed to work except that after windows would show the loading screen and right before the login screen popped up, it would reboot and would just continue in a reboot cycle.

This doesn't work anyway. Any install of windows is not going to work on any system.

I'd try memtest86.