GPU VSync

Preamble

This topic has to be followed if your setup contains at least 1 video output on your GPU (Smode interface is not included as a video output). Follow the next steps even if your setup contain multiple video output through external video card. If your setup requires to have your Smode interface on the same GPU than your video output, make sure that the display you are going to use has the same characteristic than your video output.
Example:
4k video output at 60hz requires a 4k monitor at 60hz.

Multiple video output = NVIDIA Mosaic

It is highly recommended, in case of multiple video output that need to be synchronized, to create a mosaic in inside the NVIDIA control panel
you can also use the https://www.nvidia.com/en-us/drivers/mosaic-utility/ and the command line like

configureMosaic.exe set rows=2 cols=1 res=3840,2160,60

GPU VSync

In the Smode preference/Synchro, set the requested frame rate and the option of the Sync Provider (Active or Half are the most used), according to your EDID.
Ensure to be ON AIR.
If you are not synced, this probably means that your show need to be optimized. Read more here: Use optimisation tools to accelerate a composition It is running fast? Could be faster. Read More