You'll not notice the difference. Games are not static benchmarks. Games fps bounces all over the place, watch any video, you'll see by just how much. That counter will also average the fps for a single number, but chances are if it's over the refresh of your monitor, you will not see it anyways. If it's under refresh, you can't physically tell the difference between 50 and 55fps. Your brain doesn't work that small. You'd need a considerably larger range to compare to.
It's @ 8% difference in ability, or in a game at stock 100fps, you'd get 108fps, which you wouldn't see, and if the game stock was 50fps, you'd get 54fps, which you can't see.
It's not enough OC to make a difference in 98% of games, many of which weight cores more heavily than fps, and the rest really don't use cpu speeds over @ 3.4GHz to much advantage.
Not to say you shouldn't try it, but just don't be mad if the results aren't what you were hoping for.