Just received Sapphire HD 5850. Well, it did not work on my Mac Pro early 2008 in Snow Leopard. I was using GeForece 8800 GT for running SL. Having 2 card from different manufacturers on Windows 7 made none of them usable. So, I had to switch 8800 GT with Radeon HD 2600 Mac edition, to make it work. Lesseons i've learned: 1) Do NOT mixt nVidia card with ATI car, none of them will work under windows. 2) Unsupported HD 5850 sounds VERY loud ( according to iPhone's 1G DBmeter ~50 DB when case is closed ) in SL as it's cooler running at full speed and you cannot control it unless removed from MB. 3) If you use Apple Cinema Display, prepare to swap DVI on your cards every time you boot for play. If you have a monitor with multiple DVI inputs - you should be ok. 4) If you leave HD 5850 alone in your Mac Pro - you won't see anything, not even a boot screen. 5) No chance to soft-disable the HD 5850 from Snow Leopard 6) You need 2 power cables for the HD 5850. They are included in the box, but you actually cannot plug them into the slots that Apple made for graphic cards. Luckily I had 1 on me. But for other one I had to make an 4-pin extension cable, that I connected with power cable that was powering the CD-Drive (tat cable has 2 jacks). So whoever wanted a Gaming/Work-station combo like me, this info probably will be helpful. Have fun gaming.