DNA wroteTech Guru wroteQuick Hint
Assume You Have 60hz & 144hz displays but your graphic card is outputting 48fps on both.
Frame Time on 60Hz Screen 1/60 ×1000 =16.67ms
Frame Time on 144Hz Screen 1/144× 1000 = 6.94ms
48fps Case on Both Screens
You need to wait 16.67ms for each frame to displayed on 60hz screen
You need to wait 6.94ms for each frame to be displayed on 144hz screen
Conclusion
Even you are below the monitor refresh rate the higher the refresh on display will create less stutter.
Stutter= Time of wait needed for each frame to be displayed.
Well theoretically you are right but in practice each frame from you example will be displayed 3 times on a 144hz monitor even if you update the first frame at 6.94ms you need to display in 3 times this makes the total time of each frame 20.82ms which is basically the same thing with extra lag and tearing
No need to validate things in a theoratical way , I always go the hardware method live testing bymyself.
If your FPS are below 60 FPS, then there could be stuttering, but it would be less on the 120hz monitor, because each refresh missed does not add 16.7ms to the frame, and instead adds 8.3ms to the delay, reducing the stuttering. The only time you may gain a little stuttering is if you have v-sync on and above 60 FPS and below 120 FPS, but you also gain FPS for more response, this has a little bonus and a little disadvantage too.
In short:
With v-sync and 60 FPS, they are the same
With v-sync and less than 60 FPS, 120hz is better.
With v-sync and over 60 FPS, 120hz can be better, but can be worse in ways. The higher the FPS, the more it is better.
Without v-sync, 120hz is always better.