Radeon X800 PCIe breaks OS X ability to boot on Intel i915GAVL

[Wallstreet]

I've got an Intel 915GAVL that ran flawlessly under OS X 10.4.x until I upgraded to a Radeon X800 PCIe card...now OS X simply will not boot and the OS CD locks at white screen as well. There doesn't seem to be a way in the BIOS to disable the integrated graphics...is there some kind of known conflict that OS X86 has with PCIe cards in these systems?

 

Cliff Notes: i915GAVL w/o Radeon X800 = Boots flawlessly. With Radeon X800 - Hang on white screen. Any clues?

 

Thanks.