Most games don't use more than four cores anyway. So if they both run at 3.5GHz and have more cores than the game can use, the performance will be identical. But with AMDs Mantle coming out, it supposedly supports eight cores. That would boost the performance, as it would be able to spread the workload out on all the cores.
I would probably suggest getting the 8320 too, then, some day, buy a better cooler and overclock it. Maybe we'll see some good deals in December.