I am in the process of upgrading my GPU from a integrated 6530 to either Crossfire 6770 1GB or single 6950 1GB. My main use is to play Battlefield 3 @ 1920x1080. What would be the advantage of one over the other?
System Specs are as follows:
AMD A6-3650 APU 2.6GHz Quad Core
Win 7 64bit
Not all games work well with multi-GPU setups, so he will run into problems and bad performance in some games. Plus, replacing the 6770s when they are too weak will cost more than getting a 2nd 6950, in most cases. The performance difference is hardly significant anyway. Plus, he's limited to 1GB of VRAM in CrossFire.
IF you already had one 6770 then crossfire 6770's would be the way to go but if buying new then go for the 6950 -- performance is going to be close on both but as mentioned the 6950 will only tie up a single slot leaving room to add another in the future for improved performance where the 6770's cap out and would require replacing both to get any improvement in the future. Plus some games still have issues with crossfire configs and depending on the setup you have usually run hotter and use more power.