What would be the most powerful to have out of these graphic cards combinations? :
1 x 6gb Nvidia gtx titan black?
2 x 3gb Nvidia gtx780 ti?
2 x 4gb Amd Radeon R9 290X?
1 x 6gb Nvidia gtx titan black?
2 x 3gb Nvidia gtx780 ti?
2 x 4gb Amd Radeon R9 290X?