I have a Dell Dimension C521 running Windows XP. Recently the computer all of a sudden stopped working the screen flashed and froze and than the computer shut down. Now whenever I attempt to boot up the computer it gets stuck on power savor mode and there is no display. There are several things that I have tested so far. I have removed the hard drive and attached it externally to my laptop and confirmed that the hard drive was working properly. I have reset the BIOS by removing the battery on the motherboard. The power supply boots up and the fans spin so I thought it was working properly, but when I removed the RAM and booted up the computer I did not get the three beebs to confirm that the power supply was working properly. I have tried several monitors and several different power cords and VGA cables. The computer has a built in graphics output on the motherboard and an external graphics card have used both outputs and booted up with no graphics card and I am getting no display at all. Any help or advice in what I can do would be great. I am not sure of it is the motherboard or the power supply or I am just being dumb and not doing something that can fix it. Thanks in advance. -Bryan
http://support.dell.com/support/edocs/systems/dimc521/en/OM_EN/RP333A00.pdf plug everything back up like normal. check the manual on page 47 and determine which diagnostic light code error you have.