Graphic Card problem

[afkiller]

Hello, I'm trying to install a Geforce 8800GTS but when I start my Mac Pro nothing happens, my display doesn't start and I can't select Windows in the Bootcamp. Anyway I tried starting Windows directly too and the same problem, my screen doesn't start. But if the DVI is connected in the ATI 2600XT and I enter in Windows I can see the 2 cards in the device manager, but my 8800GTS is marked with an yellow icon, saying that the drivers are not installed, but really are installed...

I don't know if I'm doing something bad, this is my first Mac

PD: I'm using an external PSU for my PCIe card, because I don't have a Apple PCI Express cable, but the graphic card works perfectly in another computer.

Thanks and sorry for my bad english.

[Tallest Skil]

You can't use a non-Apple card in a Mac Pro (without flashing).

[afkiller]

But for use it in Windows I need to flash/buy an Apple Card?:confused:

[rhett7660]

Are you not still using a Mac machine??????? You might want to try what the previous poster said.

[afkiller]

I'm using a Mac Pro 2008 with the ATI Radeon 2600XT and I want to install a 8800GTS that I have from my other PC, but only for playing in Windows with my Mac. The problem is that when I put the 8800GTS in the Mac I can't see nothing in my screen (I'm loading Windows with bootcamp).

[Tallest Skil]

You'd need to leave the 2600 in and connect any power cables the GTS needs. Then it should work. Taking out the 2600 makes it impossible for OS X's EFI to boot.

Don't worry, there are two 16x PCIe 2.0 slots. You won't have any slowdown should you put the GTS in the second one.

[afkiller]

Hello, Windows with the 8800GTS works now, but only removing the 2600 XT, if I leave the ATI connected, Windows only works with the ATI and if I connect the DVI cable in the nvidia card I don't see nothing, only removing the 2600 :(