Help Guys..........I must be doing something wrong....?????

Ok heres the deal I just swapped a my old board with a Asus A8N32-SLI . Im only using 1 video card (8800). I got everything installed it powers up but no video signal. I know my card is working cause I had it up before I installed my new ASUS A8N32-SLI. Is there a jumper setting or something for using a single video card on an SLI board? I AM TRYING NOT TO TELL MY SELF ITS THE MB? I dont have any extra PCI-e cards to test with. Please any sugestions?????? O yea and I also swapped the DVI cables too......
Help please......

Try booting with just the 1 DIMM of RAM, video card and cpu with HSF. Unplug everything else including HD and optical drives. Be sure you are plugging the psu power connector into the video card and also into the 4/8 pin cpu 12v. MB connector. Tap delete when booting up to get into BIOS. Once in BIOS, set the voltage to the RAM to mfg. specs.

Firstly, please post the complete hardware specs of your system. Make sure your PSU is powerful enough and that everything is plugged in (vid. card?) Check your timings in the bios.