I don't know how good of a solution this is to you, but i think you should get an r9 280x. It is on par, give or take, with the 770 and has around the same price of the 760. My friend just recently got to build his new computer with the same processor you have but has an r9 280x from gigabyte and I'm not sure about how it preforms on bf4 but on bf3 he said he was able to push out an average of 140-150fps on everything maxed out on the ultra preset at 1080p full AA, motion blur and everything enabled. He didnt do overclocking at all and i can imagine that you will be able to play bf4 on ultra easily over 100fps.