I have a 2009 Mac Pro with a GTX 970 installed in place of the GT 120 that came with the machine. I use El Capitan with the NVIDIA Web Drivers and I also have Windows 7 (Soon to be Windows 10) as a dual boot. Everything works as it should, no boot screen, etc., but I have read in various posts of people having some non-EFI card paired with an EFI compatible card to have the boot screen. How does this work? I've tried installing the GT 120 alongside the 970, however, this causes errors. Is there some workaround? I'm just curious as to how these people who were successful are making this work.