7950 in 5,1 Mac Pro

You will be able to put it in and it should work (without boot screen) out of the box in OSX 10.8.3 but in Bootcamp you will still be limited to PCIe 1.0.

 

It should. I have the 7970 in my 2010 Mac Pro.

http://www.newegg.com/Product/Produc...82E16814127652

I heard the MSI Lightening doesn't work. Avoid that one.

Start at page 8 of this thread if you want to see my research on this exact topic. They list some 7950's that should work as well.

http://forums.macrumors.com/showthread.php?t=1505726&page=8

 

http://www.anandtech.com/show/5458/the-radeon-hd-7970-reprise-pcie-bandwidth-overclocking-and-msaa

in some cases the drop from 8 to 4 is pretty big. Dirt in particular.

If you are gaming at 1080p, I doubt you would miss those extra FPS because most games will run comfortably above 60 fps.

At 25*14 you would probably notice.

My hope is that a EFI flash becomes available once Netkas gets his hands on the Sapphire EFI file. IN that case we will get 2.0 back in Boot Camp I think.

 

http://forums.macrumors.com/showthread.php?t=1368653