ATI DX11 RV870 is 1.6 times faster than RV770 (HD4870)
 

We've heard that ATI's soon to lunch DirectX 11 performance card, something that we know as RV870 and something that AMD calls Evergreen, should be roughly 1.6 times faster than the RV770 chip.

RV770 is the chip behind ATI's Radeon HD 4870 card and it showed quite good performance, so this 1.6 times performance increase can give you a general idea that the new chip should be quite fast. Of course 1.6 times is the best case scenario and it should be less than that in some cases, but overall this 40nm chip should be a good step forward for ATI.

http://www.fudzilla.com/content/view/15287/34/