Skyrim and all Bethesda creation engine games have issues with g-sync and high refresh rates and work best with g-sync disabled and at 60 fps , yes their are hacks and work around's but generally Creation engine games run like crap and are far removed from a smooth experience.
Save a lot. I played Skyrim at 120hz with Mighty Dragons etc and i died to a kettle. When i got my first 1000g horse i went over rocky terrain and shot up to the skybox, And fell and lost the damm horse. I stole another went to that first place where the guy in the tomb is scaring the villagers? Anyways while talking to the innkeeper i could hear a comotion, Growling so i went outside and a frickin bear had killed my horse. ***** Horses!
Also on topic i added two further changes to my Gsync settings now, First is right clicking a game exe and settings fullscreen optimizations to OFF, Google that one. And second is i only tick use fullscreen Gsync not fullscreen and windows. This plus my Low Latency Ultra mode and an fps cap 3 below the refresh rate feels AMAZING.
Hands down the above at 280hz is the best thing i experienced on PC to date. Everything is snappy and stutter and tearing free and i only have one frame of lag at 4ms.