I have seen other threads on this issue but mine is a little different.....

I upgraded my vid card and added more ram to my system. Every thing worked fine until i installed the new hardware...I get No Signal on my monitor...I have taken out the ram and even put my old vid card back in and still no video... Tried a different monitor and still same message...
My specs
Mach Speed Matrix PM9MS VIA chipset
P4 3.0
512 ram (tried to add 512 more)
GeForce 5700LE (tried to install 7600 GT)
Been running this system for 2 years and no trouble till the upgrade......

I would suggest removing all RAM and power on once. You should get BEEPS.

Turn it off and reseat one stick of the original RAM.

If this doesn't boot try a different RAM slot.

If this doesn't work try clearing the CMOS.

I tried it and nothing..I dont understand it but i guess the mobo is fubar...

Did you clear the CMOS?

I cleared the CMOS as instructed in my mobo manual..I dont understanad any of this... I have taken everything out of the mobo and put everything back in and nothing works....I am losing my mind here..

Is there a power LED on the board? Does it go on?

no LED on the board. The fans, cd/dvd rom work. I have the HD's unpluged, but they were working... I have power to everything as far as i can see...

Does the air near the CPU get at all warm?

gets a little warm. the cpu runs about 45 to 55 deg.C I have plenty of air flow to the system. I run a small fan blowing the warm air out of the case....Going to try a different cpu tomorrow....

If the CPU is warming up it indicates that it is powered and most likely working. Pointing more to some aspect of the motherboard. Also with the board not beeping makes it more suspect. Do you see any damaged capacitors on the board?