I have a 5,1 Mac Pro, it came with an HD 4870 1 GB. Sadly it seems to be the PC version of the card, so I'd like to swap it with something that has two Mini Displayports. The thing is, I know absolutely nothing about graphic cards, and I'm unsure which to go with or which ones are even compatible with my Mac. What I use the Mac Pro for: mainly music production with Logic Pro X, and lots of third party plugins. The screen: I'm currently looking for a second hand 27" LED Cinema Display. I want it to run smooth on the 2560 x 1440 resolution. Also, I have a game that I used to play here and there between sessions. It requires a quite high resolution as well (also 2560 x 1440) and it's a full 3D game. But that's less important of course Any recommendations? I've been thinking about the HD 5770 or 5780 (the price difference seems to be big). But my previous 2011 iMac had a HD 6970 M, which, according to tests, is apparently better in many points than the 5770. Thanks a lot.