they all merge differently between generations, running newer style cards net better results from the ones I know who run it successfully. Same brand gdrrr memory helps from 1 I know with this set up memory balanced pretty good running 1 2G & 1 4G cards. Had Samsung memory with latest updates got 6 gig. Pick your cards the right way helps all diffrent people experience diffrent results. If in doubt fire it up on crossfire & pull a gpu'z, load some drivers & see nothing to loose. Same gen cards might net you some ram if your lucky you may gain the more equivalent the better.
