Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I wouldn't count on Passmark GPU tests to mean much. They have quite a few cards in the wrong order as they are nothing but submitted averages. You need multiple tests for a better indicator.
 
HD5870 is still a good card. Bit slower than HD7850 in most games but no where near as bad as you think it is.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.