Have a Mac Pro 1.1 with the 2.66 dual core cpu, and 4GB memory running OSX Lion. If I use an unsupported video card - 8800GT 2nd gen on my 1st gen mac pro. Would I get a black screen?? tested the video card on a PC and it displays fine. On the Mac Pro I can hear it boot into OSX and everything just no video output. Not familiar with how the EFI works and why I get no video. Hopefully its just the wrong card ordered and not the logic board. Diag_LED Displays POWER ON, GPU DETECTED and Trickle Light is on, nothing else. which is also normal.