PC Chips motherboard

I need help.. this is very puzzling to say the least. In 2002
I bought and put together a computer using a PC Chips motherboard
M830 series socket A and a AMD 2000+ with 256 meg of Ram and 80Gig
HD.Everything worked fine till last May 2004. I took it to a computer
service and after they tried to fix the computer (which they gave up
on) they told me that I needed a new other board. The service tech
said he could not get the OS to work and he indicated that a component
in the motherboard had shorted and that I needed a new motherboard. I
proceeded to order a replacement Motherboard from Newegg. I received
the new motherboard (from Newegg) PC Chips Socket A M848A series and
installed it in the computer. I had no problem installing the new
motherboard and the old CPU (2000+ AMD). I turned on the computer and
nothing happened. no power to anything. No fans no lights nothing. I
retraced everything and found nothing wrong. I took it as a defective
motherboard and sent it back to NewEgg for exchange. 10 days later got
a replacement motherboard. I installed it as I did above and turned on
the power. Again nothing happened. The entire unit was dead.. I
proceeded to re-install the old motherboard and turned on the power
switch. Voila everything worked, fans, HD and lights. So I took it as
another defective board. Sent it back to NewEgg for replacement got
another board in 10 days and installed it again. Turned on the power
switch nothing worked. I then left for Iraq and just returned and I am
back at this computer.What is wrong??? Please help. thanks