31 fps --> 34 fps = 10%
743Mhz --> 820 Mhz = 10%

I seldom see games respond to OC as well as this.

To compare (my results):
743 core gives 40-42 in Crysis
900 core gives 50-55 in Crysis.

Settings:
x6800 @ 3,5
Crysis: 1680 x 1050, everything at 'Medium', No AA.

Regards