Microsoft added a variable refresh rate option in Windows 10 V1903 to improve game frame rate
Windows 10 Version 1903 has already provided Variable Refresh Rate option for some compatible devices. This feature is located in the graphical advanced settings of the settings application, and most users should not have found the option to add a Variable Refresh Rate compared to the old version. Of course, only some compatible devices can see the Variable Refresh Rate option and Microsoft does not specify which devices are specific, or which specific graphics cards.
In the description, Microsoft said that this feature can enable variable refresh rate for unsupported games, increase the overall frame rate of the game and reduce the jam after entering the game. After enabling this feature, you must restart the game to see the potential optimization effects. Simply put, this feature provides additional support for games that don’t have built-in support for variable refresh rates to improve the overall experience of the player’s game. According to guessing that most popular games and frequently updated games should support this feature, Microsoft has provided developers with specific API interfaces.
Via: Reddit