Well you know they say theres no such thing as overkill in PC gaming.
If you turn up alot of settings, AA+high res textures+mods etc, then even a high end card will be struggling. Look at benchmarks, there are a few games that on the highest settings average at 40-50 fps. Thats where having the 15% boost from overclocking helps alot.
BTW most games like Skyrim, BF3 etc are so easy to run on current gen hardware because their last gen games.. aka designed to run on last gen hardware which were 30+% slower. Besides they are averages, frame dips could be as low as 30 or 50 meaning overclocking can help alot.
Of course you don't need all the highest settings, turn AA down a bit and settings to High and you will gain plenty of frames. You have the power to set everything the way you want.