Whats best video card performance

[luggles]

i am upgrading from my 4870 video card. i am wondering if its better to go with the gtx 570 permi or just add another 4870 and ruin them crossfire. wich way will give me the best performance

 

[aebome]

Cross-fired 4870s will probably give you 15-25% better frame rates than a single 570, based upon a few looks at the Tom's charts and some extrapolation. However, I do know that the 4000 series had more crossfire issues than the newer 5000 or 6000 series, but driver progression since then may have helped some.