Everything you need to know about vertical sync

 Should I enable VSync, what are its side effects and possible alternatives

In most computer games, there is a setting such as "Vertical Sync". Many do not know what to do with it and notice only a decrease in the number of FPS after turning it on. In this article, we will analyze the main issues related to this topic.

What is vertical sync (VSync) and how does it work in games?

Monitors display frames evenly when each has 16.7 milliseconds at standard 60 hertz. And the video card draws each next frame immediately when the previous one is ready. In addition, the complexity of rendering is constantly changing - either the player moves around a location rich in details, or fights, or looks into some kind of chest. As a result, at first it takes, for example, 10 milliseconds to draw each frame, then 15, and then 5. Due to this unevenness, “frame breaks” appear:

V-sync 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 drawn in 1 second. This removes image tearing and makes the video sequence as smooth as possible, but increases the control response. The latter generates an input lag.

When should you turn on vertical sync (VSync)?

When the smoothness of the image is more important than the responsiveness of the game. This applies to most single-player games, except for 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 slightly slowly, with short pre-animations before they start moving. The developers do this on purpose to compensate for the input lag from the gamepad, and on the PC it also compensates for the delay from the vertical synchronization.

But in fast-paced shooters like Doom Eternal, even a small amount of input lag can make it hard to aim.

When is it better to disable vertical sync (VSync)?

When the responsiveness of the game is more important than the smoothness of the image. This applies to most competitive online projects, such as online shooters or royal battles. But not so much for many MMORPGs and other leisurely-paced games.

Esports games are usually played on monitors with a high refresh rate, where tearing is less noticeable and the control response feels noticeably better. In addition, the image at high hertz is less blurred in motion.

Is it possible to make it smooth and responsive at the same time?

Can. Many high-frequency displays are able to adapt themselves to frame output using FreeSync (for Radeon) or G-Sync (for GeForce) technologies. Then, even with the vertical synchronization turned off, there will be no gaps in the game, and the video sequence will become as smooth as possible.

If you have a monitor that supports G-Sync or FreeSync, then you should completely turn off vertical sync in the video card settings. And if you have a regular display without adaptive sync, then enable fast vertical sync (Fast V-sync for NVIDIA and Enhanced Sync for AMD), it will also remove screen tearing without increasing input lag.

Which monitor to choose: with G-Sync or FreeSync?

In 2020, NVIDIA allowed G-Sync to be enabled even on FreeSync monitors via Compatibility Mode. However, in most cases this only works over a DisplayPort cable, so at the very least you'll need a display with the appropriate input.

This is great news, because monitors with hardware G-Sync tend to be significantly more expensive than their FreeSync counterparts. In addition, software G-Sync (through FreeSync display compatibility) works almost as well as hardware. And besides, monitors with hardware G-Sync have an unpleasant feature - they often make noise, as they have active cooling of the built-in adaptive sync module from NVIDIA.

Let's summarize all of the above. Vertical synchronization limits the number of frames produced by the video card to the number of hertz of the monitor and aligns their rendering (for example, no more than 60 FPS and no faster than 16.7 ms per 1 frame). This improves the smoothness of the video sequence, but increases the input lag. In most single-player games, VSync can be turned on, but in first-person shooters (especially online ones) it is better to turn it off.

But still, it is better to use G-Sync or FreeSync technology if you have a suitable monitor. Adaptive Sync from AMD or NVIDIA automatically adjusts the screen refresh rate to match the current frame rate. True, monitors with adaptive sync are more expensive.