andrei65 :
And I don't shoot for 120FPS , i bet i can't even see that lol
You may not "see" the difference, but most people can feel the difference when sitting in front of the game controlling the view with your mouse. For me, and many others, it is more of a latency issue than a visual one, though I do see the difference if I switch the hz now, as when you get used to viewing things at high speed, your mind expects it.
However, the bottlenecks will start as low as 40 FPS on many newer games, and even down into the 20's in some rare cases. They may not linger at those FPS long, but you'll run into low spots here and there.