Here is a test from Rtings :
The LG 27UN950-B has native FreeSync Premium Pro support to reduce screen tearing, and it’s certified by NVIDIA to be G-SYNC compatible as well. You need a DisplayPort connection to achieve its max 144Hz refresh rate and G-SYNC support. Its FreeSync VRR range over a DP connection is between 50-95Hz. Over HDMI, you can achieve a max refresh rate of 60Hz and it only supports FreeSync.
Though, I would also advise to contact LG to be sure on that one.