[color:"orange"]I need more rules[/color]

Have you Googled 'boot problem' and various similar terms?


A defective power supply can spin up fans and turn on lights, but not boot the computer (no POST). This is relatively rare, but should probably be mentioned so people don't assume the power supply must be fine if the fans come on.

There is an on/off switch on most power supplies, which is possible to accidentally hit if you are moving the computer or reaching behind it to plug something in.

Especially during shipping, RAM or video cards, etc can work party loose, and can cause boot failure.

Any rattling sound when the computer is moved or tilted is probably a bad thing. A loose screw left in the case can get behind the motherboard and cause a short.

Cables are also a potential problem, though more when building or repairing a system than when it is untouched under a desk. Mice or insects can get into computers and chew on wires, though it is probably more common for cats to jump onto computers / monitors for the heat, and knock cables loose.

When plugging everything in again after moving the computer, some people just look for where stuff fits if it is not colour coded or labeled readably. They may plug the video cable into an onboard video connector rather than the video card (if they don't know the difference to start with, you would have to explain it as vertical and probably near the middle or top of the case vs horizontal and lower down).

A defective video card can cause boot problems, though it is more likely the monitor will remain black or give a 'no signal' error.