I have a Radeon 7900 Series video card. It is supposed to run 6 monitors right out of the box. Mine will not run more than 3 monitors, and it even fried one of my monitors when I hooked up a 4th. I replaced it, and still only 3 will display at a time. In order to get the fourth working I have to shut off one of the other three. I have tried every variation of connections possible, and tried multiple cords. Because I can switch one off and turn the fourth on, I know they all work and are all recognized. The card simply will not display more than 3 at a time. Please advise.