Take the 2-minute tour ×  So this morning my computer wouldn't
turn on. Pressing the power button has no affect. When I turn
off the switch at the back and push the power button after
turning it back on it seems for about half a second that
everything works: fans appear to start moving and the PSU light
turns on. This happens only for a brief moment (less than a
second) and than everything turns back off. I can repeat this by
turning Off and On the switch at the back of the case or by
unplugging the power cable out and plugging in again. There is a
small led on the motherboard which is always on when power is
connected (doesn't matter if the computer is on or off) and it
is still on now.  I am trying to diagnose what is the cause of
the problem PSU or motherboard, any ideas?  share|improve this
question Is there any "beep code?" –  David Nov 8 '10 at 16:01
5 Answers 5  up vote 3 down vote accepted  Unplug everything you
can possibly unplug, internally and externally, and remove all
expansion cards and RAM. S