Hey,
Not real savvy with it but I am running a freesync with a G-force which isnt ideal but it is the way thing turned out and that is that.
I can get 150+ FPS with V-sync disabled and using the DisplayPort cord. Make sure you check in your display properties that your refresh rate is at 144hz or it wont go any higher in the games, if you are using a VGA OC client i would look and see if that lets u change the hz also.
I may be wrong but if I remember rightly, there are different quality cables for display devices that are designed to transfer data at those high frequencies where an old HDMI at 1.4 won't be as good as a hdmi 2.0
Hope this helps,,
Goodluck