The chaps over at Tech Report got a little hands on time with AMD's FreeSync technology at CES this year. The demo was running on a 4K display with a peak refresh rate of 60Hz. If you maximize the video, you can see the refresh rate reported in the bottom-right corner. Without FreeSync, the display is pegged at 60Hz, and the rendered scene tears quite a bit. (The effect is particularly visible around the windmill's blades.) With FreeSync on, the display hovers between 44 and 45Hz, matching the scene's frame rate and eliminating tearing altogether.