I´ve purchased a new monitor with 144Hz refresh rate. My old monitor support 60Hz. It got me thinking:

How does vsync for a window work when it cover both screens?

Do developers (like myself) have to make any special considerations for this to avoid performance drops or tearing?

This question makes the assumption that vsync sync towards the slower monitor. This is at best plausible when the refresh rates has a decent common divider, such as 60Hz for a 60Hz and 120Hz screen. However if I set my screens´ refreshrates to 60Hz and 144Hz the common divider is 6Hz, ie not very impressive. Indeed, my faster monitor could be set to 59Hz, making the common divider 1Hz. If the sync however really is forced to the slower monitor refresh rate there should be tearing artifacts on the faster monitor.

Basically I´m a bit worried the desktop applications I´m making suffering from any or both of above mentioned scenarios; significantly lower refresh rate or tearing. It would be nice if someone knew how this works, or at the very least on what level the magic happens (hardware, OS, display driver, application).

Original question was asked and closed as off-topic here, suggesting asking it on Super User instead.



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