ASUS P4C800E-Deluxe Won't Post

Purchased a ASUS P4C800E-Deluxe motherboard, P4 3.4ghz Intel processor, with one gig of Corsair PC3200XLPro Dual Channel memory in two 512meg sticks, use a ATI9800 128 meg graphics card, 200 gig Western Digital Special Edition hard drive, Creative Labs Audigy 2 ZS Platinum Pro sound card, Antec Neopower 480W new power supply, new Lian LI V1000 case...tested all components except memory and processor on my other machine, when power is turned turned on, the green system board light comes on and stays green, there is a quick red LED hard drive light at the front case that turns on, then goes off, all case fans run and stay on, graphics card fan on, processor fan on, activity LED lights along both memory sticks run thru normal self check then top two LEDs stay green with no activity, no beeps from BIOS, monitor is good, tested on other system, it stays on the initial amber screen indicating and indicating no video signal....swapped out the ATI graphic card with a known good GeForce 3 Titanium 500 card from other system, still nothing...have no idea what could be wrong...anybody had this problem?

I have the P4C800 Deluxe, P4 3.0ghz Hyper-Threading and 1 gig of patriot PC3200LLC DDR 4oomhz (2x512meg), ATI AIW radeon 9600XT 128DDR agp 0.8/1.5 volt graphics card, 1 WD 80gig p ata eide, ! seagate 80gig p ata eide, 2 WD "raptor" 36gig sata drives so we are very similar in hardware, the only difference I know of in our boards is the switch to intel lan-on mb from 3coms 3c9405 lom on mine.
I got lucky when I bought the board and video card because the card is .8-1.5 volt agp and the p4c800 has a .8-1.5 volt agp slot(found info while building system, before power-up thank good) if your ati 9800 card is not compatibal it will act just like your no video signal problem, check mb spec's for agp slot then do the same for video card, also just read from ati that intel P4's dont like pci video cards,you did'nt specify agp or pci

The ATI 9800 is an AGP card and it should be ok, tested it on my other ASUS P4T board running a 1.8ghz, 1 gig of RAMBUS, and it's doin fine, talked to ASUS (Bejing) and ran the numerous tests they suggested with the board hooked up & powered out of the case, it recognized the absence of the RAM sticks with appropriate beeps, but reaction to the graphic card being gone was nill, pointing to a bad board, so back to ASUS it went...when the new board comes, I'll put the whole thing back together....ever had to take out a big Intel heatsink and processor, I'm puzzled with what to do with the "thermal Interface material that's gooped between the processor and the bottom of the heat sink...Intel says I can reuse the "thermal interface", and they don't use the grease anymore, but the stuff is just like smeared plumbers putty...pretty strange.