Ok dudes hahaha - I just threw a new power supply from dvwarehouse into my 2008 Mac Pro and the answer is YES. EVGA 750ti sc (from B&H) working flawlessly. Haven't tried the display port yet, but the DVI and HDMI work fine - no audio through HDMI. Specs are OS X 10.10.5 NVIDIA Web Driver 346.02.03f01 CUDA Driver 7.0.61. Mac Pro 2008 upgraded to 3.2 Ghz dual Quad-Core, 32gb ram, ASUS GTX 770 and EVGA 750ti sc & CalDigit Fasta USB3/Esata 2 that has 2 internal sata3 connections and I threw a OWC multi-mount into the Superdrive bay with a couple of Samsung 850 500gb SSD (connected to the Fasta card. I had to cut the side of the drive bay so the cables would reach) that have the OS main/startup disk and a second fast storage disk that redline the Blackmagic disk speed test thing. GPU - OpenCL works in all programs. I use it for FCP7, CUDA working in CS6, DaVinci 11 Lite (only runs 1 card the 770 thru trial and error buy full version and you have both), REDCINE X utilizing CUDA - both cards totalling 2176 cores and 13 multiprocessors. Pretty dope little experiment. Hope it helps... The GTX 770 works perfect since OS X 10.8.5. That was long but I wanted that info myself after I accidentally won a 2008 mac pro on EBAY that I had to FU@# with.