the 6850 would do slightly faster. but the hd 7770 is great for its price. also getting 1600Mhz ram is better.
The thing is that I already built this pc, just don't have a gpu yet. Deciding which one to get. Do you think the 6850 is worth it after these: no dx12 support, huge, loud, hot, higher tdp. In raw performance it is better, but after all of that is it? Also the 7770 is new, and 6850 used from amazon. Also, the r7 260x is 94$ Used, but I hate the way the gigabyte one looks