DEVIL MAY CRY 4 DX 10 DEMO
As you can see there is no change in frame rates going from 3.0 GHZ to 4.1 GHZ. The game engines do not rely on CPU as much as they does on the GPU to perform at high resolution and image quality.
After these early disappointments (or pleasant surprises..whichever you prefer) let us move on to the cases where the CPU frequency does in fact matter.
UNREAL TOURNAMENT III
he results are sort of all over the place, but you can still notice the jump from 3.40 to 3.80 GHZ. CPU bottleneck is not a big issue though.
There has been a follow up to this article...CPU Bottleneck Analysis revisited.


