It's actually a fairly complicated answer, in some games you may see as much as a 5 frame difference, the difference between the slowest and fastest RAM is only a couple percent at the end of the day, so in most situations maybe 1 - 2 frame difference, there's more to RAM than just the Mhz, you also got to worry about latency, which goes up as the Mhz goes up which makes the "faster" RAM almost the same speed as the "slower" RAM, you can get high Mhz fast RAM, but it's gonna cost quite a bit, and again, 1 - 3% at best difference between bestest and worstest.