The 7770 is the closest equivalent to the 6850. However, it's stock performance does fall behind the 6850 unless you are using the latest beta driver, Catalyst 12.7. Even then the 6850 may still pull ahead in some games if you are comparing it to the stock clocked 7770. The 7770 does overclock further than the 6850 does, so if you are looking at squeezing out as much performance as possible, it might be a good choice.