Frequency can affect performance, but it depends on the game. The more dependent the game is on the CPU, the higher the potential performance improvement. It is also not 100% efficient; meaning if you increase the frequency by 10% your performance will not increase by 10%.
Going from 3.2GHz to 3.4GHz is a 6.25% increase in performance. So in the perfect scenario gaming performance will increase by 6.25%. In the real world performance gains will be from 0% to probably 3%.
Bioshock Infinite is an example of a game that is known for not caring too much about the CPU performance. Below are two benchmarks for overclocked i7-3770k and FX-8350 CPU with a GTX 680. Note that you do not get much performance increase from overclocking the i7-3770k. Going from 2.5GHz to 4.0GHz (60% increase) the frame rate increases from 65 FPS to 69 FPS (6.1%). Going from 4.0GHz to 4.5GHz does not increase game performance at all; so 500MHz = 0 FPS. The performance increase is even worse for the FX-8350. Starting at 2.5GHz you would need to increase the frequency to 4.5GHz to get 1 extra FPS.
http://www.techspot.com/review/655-bioshock-infinite-performance/page5.html
SimCity is known for being a CPU intensive game. It is also known for taking a dump of those people who loved that series in the past because EA forced SimCity (a traditionally single player game) to be an online game which I suppose ruined the entire experience for veteran "SimCity-ers".
Again, starting with a base frequency of 2.5GHz, the game does experience an increase in performance as the frequency goes up. When the i7-3770k is clocked to 3.5GHz (40% increase), the FPS actually increased by 13 FPS (43%) which is pretty much unprecedented. I think you will find it extremely difficult to find another game than can do that. However, going from 3.5GHz to 4.5GHz only yields another 2 FPS. As for the FX-8350, going from 2.5GHz to 3.5GHz provides a 8 FPS increase (33.33%). However, going from 3.5GHz to 4.5GHz (28.6%) yields another 8 FPS increase (25%). FPS increases scales better on the FX-8350 than the i7-3770k, but as can be seen by the charts an i7-3770k @ 3.5GHz still beats a FX-8350 at 4.5GHz.
http://www.techspot.com/review/648-simcity-performance/page4.html