Are you sure that V-Sync is on? Video card drivers can override the game setting. You can have Steam display the frame rate and make sure that it matches the rate in the game options.

I remember, years ago, someone had the same problem and, as I recall, turning on V-Sync fixed it.

yes i have had v-sync on

You could have Steam verify the game files. I doubt that it will help with this, but no harm in trying it.

If you're sure that V-Sync is actually on, you could try going into the video card drivers and limiting the frame rate there to 60 Hz. That's really just another way to get the same effect as turning on V-Sync, so it may not help either, but that's the only other thing I can think of.