Using high-quality settings with a GeForce GTX 580, we find Dirt 3 to be more GPU-dependent and as a result the slower processors do not sacrifice much performance. The AMD A8-3850 for example, when configured with DDR3-1866 memory was able to match the Phenom II X6 1100T.
Side note: When we first tested Dirt 3 using the dual-GPU GeForce GTX 590 we found the Athlon II processors really struggled. However since then the game has been patched and it appears that this might have corrected the poor performance that we saw on lower end processors.
The AMD A8-3850 (DDR3-1866) was considerably faster than the Athlon II X4 640, providing 11% more frames per second. That put it 3fps behind the Core i5 750, but also 2fps faster than the Phenom II X6 1100T.
The results we recorded in Battlefield: Bad Company 2 were similar to Dirt 3's. We find that as long as this game is powered using a quad-core processor, the performance is satisfactory. Such is true for the A8-3850 (DDR3-1866), which delivered 88fps, placing it alongside the Core i7 920 and i5 750.
Civilization V is very CPU-dependent and despite using high-quality visuals, the GTX 580 isn't the weak link here. Although the A8-3850 provided highly playable framerates and managed to outpace the Athlon II X4 640, the Llano chip was still a fraction slower than the Core i5 655K and well behind Intel's heavy hitters.