What likely would be the problem if the server you just purchased is rebooting each time it is powered on?

On a server I just purchased they likely have the correct power supply in the unit or it wouldn't fit. And as Iko5000 pointed out, most server hardware does not reboot when a PS is bad, if its bad, it wont power on. However, a bad memory check on a system will cause the system to reboot if the bios is set that way and the memory fails post tests.