But years ago we found machines that did that when a long list of issues were the cause. The causes are not limited to this list. GOOGLE (search) each one.
IDE CABLE UPSIDE DOWN OR OFF BY ROW, PIN
CARDS NOT PLUGGED IN
SHORTED MOTHERBOARD MOUNTING (BAD MOUNTING)
HOW DO I TEST A PC POWER SUPPLY?
Hope this gets you started.
A buddy of mine asked me to look at his PC because it would not turn on. All power cords are plugged in, and when the power button is pressed it lights up, but quickly goes out. Is the power supply burnt out? Thanks in advance!