Both graphics cards work fine. Quadro 4000 is newer and is official Mac version
GTX285 is good - and benefits from a 2nd DVI port and is a bit cheaper. However, you can only get PC re-flashed versions of the GTX285 now as the Mac edition is no longer sold and almost impossible to find.
Im testing a GTX480 (re-flashed) and might be a GTX570 available in a few months...

However - testing depends on your hardware OS and SSD and movies etc.
(both are very similar performance though...)


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