Dual-Graphics or..?

Hey, I'm awfully new to this stuff.. so don't hate me if the answer is obvious and I'm just dumb o-o

I was wondering what would give me better performance (gaming-wise) a radeon 7750 or 7770

-I can use dual-graphics with my apu (A10-5800k with 8gb of 1866mhz ram) with the 7750, but not the 7770-

Would this make the 7750, the cheaper choice, perform better with dual-graphics than the single 7770 could?

Thanks ahead of time :)

I thought that you can use 7750 in dual graphics mode only with Richland APU A10-6800K, while the best graphics to dual with Trinity platform was 6770.

I'm afraid you can't crossfire the A10-5800K with either 7750 or 7770.

They only crossfire with the 6670 Link to AMD

 

This says otherwise.. http://www.tomshardware.com/forum/id-1688717/review-amd-a10-5800k-7750-msi-working-dual-graphics.html