Well i just tested Batman AA with both 197.75&257.15
With 197.75
Minimum:40 FPS
Maximum:107 FPS
Average:71 FPS
With 257.15
Minimum:31 FPS
Maximum:101 FPS
Average:66 FPS
now i'm off to test Arma 2
Update:
Arma 2 Run's like a slide show with 197.75,and with 257.75 it was stuttering&the benchmark crashed the game
this occurs in the Beta 70709 and the 1.05 Official Version on Steam