I have been trying to figure this out for 3 days. I will try to explain the best I can. I have a Dell XPS 720. It has 2 nvadia gtx 8800 graphics cards. Each card has 2 ports. So there are 4 ports total. If I am not able to get an image out of 1 of the ports on 1 card and another port on the other card. 1 port on one of the cards produces an image but there are lines and dashes all over the screen. If I unplug from this port and plug into another port after the computer is already running the image is perfect. However if I restart the computer the port that has the perfect image no longer works. I have to plug back into the port that produces the image with the lines and dashes all over the screen. Wait for a minute or two then unplug from that port and plug back into the port that produces a good image.
Sorry if I am not clear on this but I have never seen anything like this and is kind of hard to explain. Any help out there is more than greatly appreciated.