Tv does not work the same way as 3D Engines.,
in TV 30FPS are enought to
see a fluit image.
In a 3D engine 30FPS dont look fluit in action games.
You need at least 60 to 70 FPS to see no difference.

But shure, FPS over 120 dont have much improvement.
There are not many games, where you would notice
a difference.