if you really want to save the 7950 is not much slower than the 7970. less than 10%. i moved the 7970 to my intel and bought another 7950 to replace the temp 7770. i had the 7970 in my amd rig for awhile.
BF3 SP and Coop, 4GHz quad is fine. MP, those extra cores help. it can push a single 7970 to max usage.