Why and when to enable VSync, and what side effects it has
All computer games have such a setting as “Vertical sync”. Many do not know what to do with it and only notice a decrease in the number of FPS after turning it on. In this article, we will analyze the main questions regarding this topic.
What is vertical sync (VSync) and how does it work in games?
Vsync affects the rendering of frames by the video card and makes it “take your time”. That is, if the monitor has a refresh rate of 60 hertz (60 updates per second), then no more than 60 frames will be rendered in 1 second. This removes gaps in the image that occur due to the difference between the render time of each frame and the output time (see illustration above).
Monitors output frames evenly, when each one has 16.7 milliseconds at a standard 60 hertz. And the video card renders each next frame immediately when the previous one is ready. In addition, the complexity of rendering is constantly changing – either the player moves through a location rich in details, then fights a battle, then looks into some chest. As a result, at first it takes 10 milliseconds to render each frame, then 15, and then 5. If you enable vertical sync, a new frame will be displayed on the monitor only every 16.7 milliseconds. This will make the footage as smooth as possible, but will increase the control response. The latter generates an input lag .
When should I turn on Vsync?
When smoothness is more important than game responsiveness. This applies to most single player games, except first person shooters. Maximum smoothness will allow you to enjoy the plot without being distracted by graphic artifacts.
In role-playing adventures like The Witcher or Assassin’s Creed, characters even move a little leisurely, with short pre-animations before starting to move or turn. The developers do this on purpose to compensate for the input lag from the gamepad, and on PC it also compensates for the vertical sync lag. But in high-paced shooters like Doom Eternal, even a small input lag can make aiming very difficult.
When is it better to turn off vertical sync (VSync)?
When responsiveness is more important than fluidity. This applies to most competitive online games like online shooters or battle royale. But not particularly for many MMORPGs and other leisurely paced games.
Esports is usually played on monitors with a high refresh rate , where gaps are less noticeable and the control response is noticeably better. In addition, many high-frequency displays are able to adjust themselves to frame output using FreeSync (for Radeon) or G-Sync (for GeForce) technologies. Then, even with vertical sync turned off, there will be no breaks in the game, and the video sequence will become as smooth as possible.
Let’s summarize all of the above. Vertical sync limits the number of frames issued by the video card to the number of monitor hertz and aligns their rendering (for example, no more than 60 FPS and no faster than 16.7 ms per frame). This increases the smoothness of the footage, but increases the input lag. In most single-player games, VSync should be turned on, and in first-person shooters (especially online) it should be turned off.
