Any computer dudes out there?!?! Help!

here's what I do daily when checking out PC's
1 all connectors plugged in
2 power supply light (or use tester) you can have a good 5 volts but bad 12 volts
3 unplug power and reseat memory chips.
still won't work I go to basic's
unplug or remove cd, hard disk, video card,keyboard mouse and memory , oh yeah the usb cables and network cable
4 try to turn it on, you should have a memory beep. if not either bad motherboard or CPU
5 if it then posts or looks like it wants to run, unplug, add 1 stick of memory in a different slot and test
if that doesn't work then it could be memory went south. if it does post then try the same for
each component ie video, hd, cd until you find the bad part.
hope this helps