Power.
Motherboard.

Two annoying little problems that make computers and as indicated above, create issues.
1.) Power supplies can and do fail, so I recommend and demand of most peeps with issues like this to go and get a fairly new Antec. Never a problem with those.
2.) Motherboard may be a dead one, usually dying from issues regarding too much power. In surges, both devices may die.
3.) Heatsinks are known to arouse issues. They can short motherboards if applied incorrectly or are not made for the semiconductor in question. I actually owned three for one board and two created issues. (After my ECS board died in an unfortunate power current issue, I took the chance to replace it with a very nice ASUS P5P800 SE.)

You were smart to use the board on a non-metallic surface, few try it for shorting issues. Best of luck.

Hi,
I've got a similar configuration as bradnick (same mobo + 512 MB + same CPU + geforce fx 5200). Worked almost fine since purchase on November 2004.
Video card is ok, has been checked on another pc. My PC starts, HD LED lights up for less than one minute but screen says no input signal and then nothing but the noise of the fans of the power supply and CPU ! Did not manage to boot up with the Windows XP pro sp1 CD.
Checked memory slots but they look ok.
Any solution ? Thanks.