I was wondering if anyone could help me. I just purchased a new ASUS P4C800-E Deluce MB and installed it into my case. I couldn't get it to post or anything, not even video and no beeps. So I stripped it down to the MB, PS, Chip w/Fan, one mem module and the video card. I get a green light on the front, the CPU fan runs, but nothing else happens. No beeps, no video, no nothing. Any advice? I checked the MB for any signs of damage and there aren't any. Could this simply be a bad mobo? TIA.

Re-check the little posts that the mobo is mounted on. If you have any false contacts between these (grounded) posts and your mobo, it will not work.
Also check that you have connected that bunch of small wires (HD control/reset/on-off/speakers etc.) If they are the wrong way around you may run into similar problems.
Did you connect the extra P4-powercable?

Take the memory and g/card out (seperately).. see if you get beeps then, failing that and the multi-functions are on right (power/reset switches etc) like RBS said, then I'd say the board was defective when you got it, or you've shorted it.

...ahh... figured it out. The new motherboards need the 4 pronged ATX12V connector connected to the mobo. Now everything seems to work fine. Thanks for the help though!!!