AMD Radeon HD 7850 2GB or Nvidia GeForce GTX 660 2GB

7870 GZ edition
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202025&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

Bench marks 7870 vs 660

http://www.anandtech.com/bench/product/857?vs=783

7870 XT is very close to 7950
http://www.newegg.com/Product/Product.aspx?Item=N82E16814131484&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=