4G Ram post & boots, but no video

Running Visa 64 Ultimate, Asus Crosshair MB. I've been running 2gig, but decided to go ahead and toss 2 more in there. Everything post fine, boots, etc. Nothing locks up, but I have no video signal.

I've tried HDMI/DVI/ANALOG...nothing. I disabled SLI and booted with one vid card, but still nothing.

Machine will boot with 3 (1gig ea) ram and runs great but when I plug in the 4th one...no video. Any suggestions for a novice tweaker.

(Graphics 2x7900GTO)

Thx

bump up the mch/nb voltage in bios.

Hi Bonefish, I have the exact same problem at the moment, i would love to know how you fixed your problem and what caused it?

You can also check my thread about this issue......

http://www.ocforums.com/showthread.php?t=536252

Unplug Psu from wall
Remove ram
Remove CMOS battery from mobo for about 5-10 minutes
Put CMOS battery back in
Install ram (all 4 sticks)
Plug psu back in wall

Power On, go into bios and set evrything back up.