3 monitors, 2 video cards, Windows 7

[Guest]

I have 2 video cards, both the same. I am running 2 monitors with DVI and a DVI to RGB adapter on a set of projectors. I can hook the monitors on the first video card and the projector on the second, but the image on the projectors which is display 3 does not work. If I add the projectors as the second display on the first card they work, but if I then plug the 2nd monitor into the second card, the 2nd monitor works and the projectors (card 1 output 2) stop working? Any help would be greatly appreciated.
Thanks

 

[jay2tall]

What cards are they? What motherboard do you have? Do the drivers think you are trying to run SLI or Crossfire? If they are the 2nd card won't output. You have to make sure SLI or CF is disabled.