I ran across an article, that I wished that I had bookmarked, that showed an interesting performance curve relative to what I believe was refresh curve in ms and as the FPS approached the time in ms started to decrease to the point that the curve was more or less flat. You could say that it was like revving the engine but not going any where so from 40 to 60 there was a worth while performance increase that was almost double but to double after that you would have to hit 120.
The thing is over 60 is a feel good number where the returns are little and the excess is of little value that is converted into heat which can degrade performance over longish playing times. See the thing is if you uncap and ask the card to do 120 it will attempt to do so because you told it to. What ever the card can’t render is converted as I said into heat and card manufactures are smarter than their customers so they put in stuff into products, like auto throttle, that will automatically decrease the output of the card that most will see as latency, dropped frames, or as a visible stutter.
60 is more than enough and anymore is just showing off… unless you are one of those that can tell the difference between new and old Coke. 