Is there a visible difference between 60 FPS vs 120 FPS? I am going under the assumption that the monitor is your standard 60 Hz monitor. I've heard arguments that you would want a higher FPS for first-person shooter games then 60 FPS. I am looking for a good answer that actually has some technical merit behind if possible.
71 Answer
If you compare a stable 60FPS with a stable 120 FPS you should see no difference at all.
A 60Hz monitor refreshes the screen 60 times a second, so at 60 fps there is a frame drawn every time the screen refreshes, and at 120 fps there is a frame drawn every time the screen refreshes and once in between refreshes, so it's not shown on the screen but does get drawn.
In the case of fluctuation both could get some tearing if the frame is half drawn on the screen refresh.
People want certain frame rate locks in certain games because of the game engine bugs that manifest at that frame rate.
If you can get a constant 60fps (ironed out with vsync to prevent screen tearing when it goes over 60) you should be good to go, on a 60 hz monitor you won't be able to see the extra frames unless they manifest as screen tearing.
