Have you tried GraphicsEnabler yet?

I had the same problem with my 8800M 512mb. Nothing would work (natit, NV, EFI). I actually had to use graphics enabler.


in my apple bootlist i used <key>graphicsenabler</key><string>y</string>

However... it didnt' work for me until I actually typed in graphicsenabler=y on boot and I can't remember but it was something along the lines of

"graphicsenabler=y -pci=0" or "graphicsenabler=y pci=1"

I remember that on my laptop graphics enabler didn't work because I had to tell it the right PCI.

I hope this helps. .... my 8800M GT is running all resoultions with native in place and vram qe/ci