That is a weak CrossFire. For Bioshock Infinite, it'll be just barely playable at maybe 720p @ Ultra. If you lower the quality, you can play fine on 720p and maybe a bit higher. 1600x900 will be pushing it. As for Crysis 3, no chance.
Slightly over, but it's good. If you must stick to the budget, lower the GPU to a GTX 650 Ti.