Motherboard will not post

strip the system down to bare minimum, 1 stick of ram, no pci cards and one graphix card, or integrated graphix if available. attach a speaker to the mobo speaker leads and listen for beeps, if there are no beeps, then the problem is the processor (or, possibly, the power supply). if there are beeps, you can look up the beep code on the mobo's manufacturers' website.

also, ensure that your power supply is sufficcient for your cpu/graphix card. if it is a multi-rail power supply, it may have enuf overall power, but not enuf power to one particular rail.

Turn it off. Remove the AC power-cord.
Disconnect all the devices (floppy, disk-drive, CD-drive).
Remove any add-on PCI cards (modem, network, TV, 2nd video).
Remove ALL the RAM.
Reconnect the power, and turn it on.
Try to POST -- if it is not "dead", it should "beep" a few times, due to having _NO_ RAM installed.
Turn it off.
Remove the AC power-cord.
Add ONE stick of RAM.
Connect the AC power-cord.
Turn it on.
Same "beeps"? Different? No beeps?