Hi all I just upgraded my Mac Pro 5.1 (flashed) system to a hex X5670 2.93GHz. But I see little improvements over my quad 2.66GHz for FCPX editing. I have a Leadtek GTX 660Ti 2GB and 20GB PC1333 RAM. My Mac Pro is using SSD for OS and scratch disk. I am thinking of switching to the AMD R9 270X. It seems to have a similar power consumption to the GTX 660 Ti and I'm thinking it may serve me better for FCPX editing work. Does anyone know if the AMD R9 270X card can run on the Mac Pro 5.1 out of the box without any firmware flashing? I am ok with not having a grey screen on bootup. If yes, what brands? Also please share your experience. Thanks!