Just set vertical sync to on and make sure g-sync is enabled under the setup g-sync menu. 

Sajin
Just set vertical sync to on and make sure g-sync is enabled under the setup g-sync menu. 

 
That no longer stands with a G-Sync monitor. You want Vsync set to Fast under Nvidia global settings. Vsync off always in games. 8:00 mark https://www.youtube.com/watch?v=WpUX8ZNkn2U Before or if it goes into a big debate. No offense to you or anyone else. But, I will take his word for it since he works at Nvidia himself and knows his stuff. 
 
 

XrayMan
 
I like turning off V-Sync only because it makes the games FPS go up. Downside is the game may at times show some minor screen tearing.

only if you don't have a gsync monitor! gsync is amazing, you don't realise how awful lag is being capped at 60fps with vsync on. games feel totally different, so much more fluid.
 
Only downside is that on some simpler games/applications, your card will generate more heat by spitting out hundreds of fps you might not necessarily need. Vsync mode 'Fast' is good, though I often find using nvidia inspector framerate limiter v2 or precision xoc framerate target to be better, as you can set the upper limit to balance fps/temps. I have a 144hz gsync monitor, but often set it to 100-120fps just so the card can run a little quieter