3DMark warns you when vsync, FreeSync, or G-SYNC is enabled. These settings can cap the frame rate when the benchmark frame rate exceeds the monitor refresh rate, resulting in a score that is too low. Note that if the framerate during the test never reaches the maximum monitor refresh rate, the score may appear normal but you should be cautious when doing comparisons between systems as there is a slight additional driver overhead from supporting variable refresh rate and this can influence the result. For accurate and comparable results, you should disable these features in your video driver settings before benchmarking, unless your goal is specifically to investigate this extra overhead or compare two systems that both support variable refresh rate technologies.

Sometimes, 3DMark will warn you that G-SYNC is enabled even though you do not have a G-SYNC compatible monitor. This issue is a result of a quirk in the NVIDIA driver settings.

When you change the rendering quality, it turns on the internal G-SYNC setting regardless of the type of monitor you have. If you don't have a G-SYNC compatible monitor, the setting does nothing, but you won't be able to turn it off again from the settings. 

There are a few ways you can resolve this issue.

  1. Ignore the warning if you are sure you do not have a G-SYNC display. 
  2. Reinstall NVIDIA drivers using CUSTOM -> PERFORM A CLEAN INSTALL
    This will reset all settings, including the hidden G-SYNC setting.
  3. Use the NVIDIA Inspector utility to turn off the hidden setting.