At 1920x1200, the HD 7770 felt an 85% bump in Crossfire, enough to overcome the HD 6870 by 31% and GTX 560 Ti by 29%. The dual HD 7750s outpaced the same cards by 9% and 7%.
Dirt 3 seems to favor GeForce solutions, so the Crossfired HD 7770 was only 13% faster than the GTX 560 Ti yet 57% faster than the HD 6870. Similarly, the HD 7750s were 15% slower than the GTX 560 Ti and 18% faster than the HD 6870.