Re: Dimension 5100 won't power up
Are any of the four Diagnostic lights on the back panel lite, are there any 'Beeps'?
The Dimension 2400 Troubleshooter and Diagnostic Guide, is HERE
<ADMIN NOTE: Broken link has been removed from this post by Dell>
You could try the following:
Unplug the cord from the power supply, hold the power button in for about 15/20 seconds, open the case, unplug the 20-pin power connector from the motherboard and jump the Green wire to one of the Black wires, reconnect the power cord and power the system, if power supply's fan and the hard drive runs, then the PSU should be good.
Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper.
Power supply checks out and the system still does not work, again remove the power cord, hold the power button in for several seconds to discharge the residue power, reconnect the 20-pin connector to the motherboard.
Remove all the PCI cards, the video card [if applicable], memory, all peripherals, disconnect the data and power cables to all the drives, check that the front panel cable is connected to motherboard, with nothing else connected to the system, reconnect the power cable and power the system on.
If you do not get any beep codes and/or there is no change in the diagnostic lights, then it would appear that the motherboard has died.