I think the key is getting your overclock on a 6 (including 8) core processors as high as possible. As these particular processors can be more of a challenge to overclock, given the power draw with heat output especially when overclocking on the higher limits. The higher limits (e.g. 4.5GHz) allow any given core to go fast as possible at single core tasks.
Point I am making is that if you have a 6 core with a low overclock, you will be limited by single core performance.
I have been looking at several new games lately and monitoring the load on each core/thread, on many of them they are usually maxing out one of the cores 100%, maybe another two cores 75%, then another few core can vary from 30-50%. Just going on my own observations it appears there is one main thread which hammer the hell out of one of the core, and the others are loaded up accordingly.
In my case was the reason why I dropped trying to cool an 8 core with higher air and move to higher end AIO to get those extra 500-700MHz to make the most of anything that uses a single core for any game and application. I really didn't want to fork out for 6 or 8 core and then be cut short by a 4 core processor.