We used the AMD FX-8150 for our CPU scaling test and as shown above, performance continued to improve as we pushed the chip up to 4.5GHz alongside the HD 7970. Once we dip below 3.5GHz, the frame rate starts to dip quickly until we end up with "only" 62fps at 2.5GHz -- still perfectly playable, of course.
The Core i7-3960X unsurprisingly topped our CPU graph, followed by the i7-2600K and i5-2500K. The i7-920 still holds its own, while the FX-4170 is AMD's fastest entrant, narrowly besting the Phenom II X4 980 and X6 1100T, which outperformed the FX-8150. The Athlon II X2 and X4 performed poorly at 70fps and 75fps.