Hi! Using the 10.8.5 is not good idea because of tearing video... As for me I have downgraded OS (I use MacPro 4.1 so it is not a problem) to 10.6.8 and now it runs much better. And what about Maverics, is it OK? I know that its only testing now, but I want to bay gtx680 wich runs only on 10.8.5 and 10.9, so this question is actual for me (and I think for most users)...
