By default the Intel Core i7-3770K processor comes clocked at 3.5GHz. Right away we found that reducing the clock speed resulted in a considerable drop in frame rates. There was a 14% drop in performance when going from 3.5GHz to 3GHz and then an even bigger 19% drop from 3GHz to 2.5GHz.
Naturally, we felt that overclocking the Core i7-3770K would lead to increased performance and help us unlock the true potential of the GTX Titan. However this was not the case, as the i7-3770K clocked at 4.5GHz was just 5% faster than the standard 3.5GHz configuration.
Whats more surprising is that despite appearing very CPU bound, SimCity only used four cores. While monitoring CPU utilization we observed it was generally low at around 20%. If the game was fully utilizing four cores, the utilization of the i7-3770K should have been around 50%, but it was less than half that.
The AMD FX-8350 comes clocked at 4GHz and at that speed it was much slower than the Core i7-3770K. Overclocking the FX-3850 to 4.5GHz was necessary to reach 40fps, so this suggests that AMD users are best off dabbling in a little overclocking.
Yet still, we found CPU utilization to be rather low. Of the three to four cores that the game was using we only saw ~70% utilization per core.
The Core i7-3960X was the fastest processor tested averaging 44fps, while the i7-3930K and i7-3770K were a close second with 43fps. The Core i5 processors performed exceptionally well as the i5-3570K averaged 41fps and the i5-3470 39fps. The fastest AMD processor tested was the FX-8350 which averaged 36fps, while the FX-4320 was only slightly faster than the old Core i7 920.
Those using older FX processors such as the FX-8150 or even a Phenom II, including the X6 1100T, are going to have a really hard time after a few hours of playing, as larger cities bring them to their knees. Dual-core processors are fairly useless and even the Core i3-3220 was limited to just 23fps.