Sometimes machines stop working, or you install a new piece of hardware and just can’t boot again. That’s when you have to get back to some basics to troubleshoot what the problem is. Yesterday I saw a machine that wasn’t booting. It would display the splash screen and then power down. They had a new video card on a previous diagnosis using the indicator lights on the back (Dell). The add on card seemed to work, but the system was just not booting. Someone had suggested to them that it was a power problem.