Original Commentary

If you have a computer with no video, the first thing you want to do is listen for beeps when it starts up. A machine will normally beep once or twice on POST. Anything more than that is a diagnostic code and usually indicates a motherboard or memory problem. You'll also want to hit the caps lock key a few times and see if the keyboard lights respond. If they do, then the computer isn't totally frozen and it may be a video issue - Terrence

Modern Commentary
Do computers still beep on startup? Did I turn that off on my computers long ago? I mean, shutting them down doesn't even properly shut them down any more... - Terrence