Run the check
Identify an application and scene where the split can be repeated.
Record frame rate, refresh setting, and available synchronization mode.
Change only one sync option and compare the same moving scene.
Read the result
If the line changes with sync configuration, investigate the render path.
Limits and next step
A browser refresh estimate cannot diagnose every game's presentation pipeline.
Repeat the check after changing one setting or connection. Keep a record of what changed before deciding whether the device needs service.