vsync is a load of cobblers imo, it introduces filthy input lag and makes me play worse. I use afterburner (rivatuner underlay) to limit my fps to 120. No need for vsync that way
No idea why nvidia didn't just implement this as a feature rather than 'adaptive vsync'.. I guess it's not as 'marketable'.
To clarify vsync slightly, it locks the frames to the refresh rate. if you unable to meet the refresh rate in frames then you are locked to a lower multiple instead. For 60hz monitors that means when you fall to only being able to produce 59fps you get locked to 30fps. Console style. Adaptive vsync just switches off the vync when you can't meet the refresh rate.