as stolen from somewhere else>
FRTC will try and cap the frame rate to whatever you set it to.
The clock speeds on the card will be automatically dynamically adjusted based on what is needed to maintain that frame rate at any given time. So if the demand is lower, then the card will downclock, because that's all that it needs to maintain that FPS, or vice versa - boost the clocks to maintain that frame rate under a more 3D intensive scene. Useful for saving power and also for older games/applications which don't demand super high frame rates.
Adaptive Vsync will automatically enable or disable Vsync as needed. With traditional Vsync, it attempts to eliminate "tearing" by capping the game's frame rate to your monitor refresh rate. But...