Mac Pro Dual Displays I have a 2007 Mac Pro that shipped with 10.4.7, and an ATI Radeon X1900 XT graphics card. The card has two DVI outputs for a dual display setup.

I recently updated my OSX to Snow Leopard and have never tried to connect a second monitor.

Now, when I try to connect a second monitor, OSX does not detect it. Any help with this issue would be greatly appreciated.
Try putting your main screen in the slot that does not work. If you still get no video i think the port on the video card is dead.

What size screens are you using though?