What Is “VSync,” and Should I Turn It On or Off? | Tutorial
If you use 3D applications or games, you may have come across a strange option in the video settings. It's usually called “vertical sync” or “VSync” for short, and it's not immediately obvious what it does. So why is this option here, and what does it do? What forms does it take?
More importantly, should you turn it on or off? We're here to tell you.
What VSync Does
To start, let's look at how graphics are processed in your computer. Your computer or laptop has a way of rendering graphics to a screen. This may either be integrated graphics within your processor or an independent graphics card. The graphics processor's main job is to “paint” visuals onto the screen. The reason you can read this article is due to a graphics processor telling your screen to draw it!
When you tell your graphics processor to render a 3D scene, it will process full drawings, or “frames,” as quickly as possible. It then gives these frames to the monitor to process. The result is a slideshow-like effect of rapid-fire frames that give the appearance of animation, like a flipbook. The rate at which the graphics processor can output frames is called “frames per second,” or FPS for short. The more frames your graphics processor can output, the smoother your games will look.
Your screen is always trying to keep up with the frames your graphics processor is producing. The maximum amount of frames it can display is depicted in its refresh rate, which is usually defined in frequency or “Hz.” The ratio is 1:1, so a monitor at 60Hz can show up to 60FPS. The refresh rate is stated in a product listing like the following image.
When They Conflict
The problems begin when your graphics processor begins to output more frames than your monitor can handle, such as 100FPS on a 60Hz monitor. Your monitor may struggle to keep up with the flow and end up out of sync between two frames. This is called “screen tearing,” where an image seems to be “cut in half.”
This is where VSync comes in. VSync aims to match the graphics processor's frames with the refresh rate of the monitor to fix any syncing issues. This is typically done by freezing the game engine or buffering frames until the monitor is ready to output the next frame.
Advantages of VSync
As stated, VSync is worth a try if you're experiencing screen tears. This will bring your graphics processor down to the same level as your monitor and will allow them to work better in unison, thus eliminating screen tearing when done right.
It can also be useful in applications (such as very old games) where your graphics processor severely overpowers the graphical demand. Because graphic processors go as fast as they can, rendering old scenes may result in exceedingly high frame rates. This can cause your graphics processor to overheat, as it outputs frames at an incredibly fast rate. Enabling VSync will cap the FPS to the monitor's refresh rate and stop the excessive strain on the graphics processor.
Disadvantages of VSync
Because VSync makes frames wait for when the monitor is ready, this can cause problems. You may find that your inputs, such as key-presses and mouse clicks, are slightly delayed. This can be fatal in games that require reflex and snap reactions to play. There are some technologies developed for VSync to help reduce this lag, but it's worth keeping in mind if you enable VSync and notice your actions are less responsive than before.
VSync is great when the frame rate exceeds the monitor's refresh rate. However, if you come to a graphically intense moment, and the frame rate drops below the refresh rate, the graphics card will drop it down further to best match the monitor's preferences. The result is an even bigger drop in frame rate during intense moments. Technologies such as triple buffering can help prevent this, but it may not be an option everyone has access to.
Different Types Of VSync
The above descriptions refer to the default Vsync function that has existed for years on PC. However, more recently, the hardware powerhouses of the games industry have begun coming up with new and improved forms of Vsync that negate some of those problems. Here's what you need to know about them:
Nvidia Adaptive VSync
Adaptive sync is a feature exclusive to Nvidia (it can be found in the Nvidia Settings app). It uses Vsync when your frame rate exceeds your monitor refresh rate, but then instantly switches it off each time your fps drops below your monitor refresh rate. This means you don't suffer stutters from the super-fast, but super-steep, FPS drops caused by standard vsync, which is vital, particularly when online gaming.
Nvidia Smooth Vsync
Smooth Vsync is another Nvidia exclusive, this time with minimal stuttering in mind. This feature works out what frame rate your game can stably run at, then maintains the frame rate there, bumping it up only when it knows that your GPU can sustain the higher frame rate without dropping.
This groundbreaking tech came out a couple of years ago and does the ingenious work of adapting your monitor refresh rate to your gaming framerate. The result is a completely smooth gaming experience (if your GPU can handle it, that is), with no screen tearing, stutters, latency, or sharp FPS drops that accompany standard vsync. The catch is that you need a G-Sync-capable monitor and Nvidia GPU to use it.
If you want to know more about G-Sync, we wrote a whole article about it here.
See above. This is AMD's direct answer to Nvidia G-Sync. While the results are great, you'll require a FreeSync-capable monitor and AMD GPU to take advantage of FreeSync.
AMD Enhanced Sync
Using some of the FreeSync technology and applying it to monitors that aren't FreeSync-capable, Enhanced Sync prioritizes a smooth game experience and will allow for the occasional screen tear to prevent the stutters that can result from regular VSync. So there's a little more tearing than Vsync but less stuttering. It all depends on your priorities!
Should I Turn It On or Off?
So, should you turn VSync on or off? As you can see, it's very much a case-by-case basis. In general, if your graphics processor is rendering more frames than the monitor can display, it may cause excess heat and screen tearing. Try enabling VSync either via the software or your graphics processor's settings to calm things down.
However, if the frame rate is below your monitor's refresh rate, there's little reason to have it on. There's no tearing or over-processing to fix, so the only effect VSync will have is potentially worsening your frame rate and causing input lag. In this case, it's best to keep it off.
Of course, given how easy it can be to switch VSync on and off, it's worth trying both. Now that you know more about how VSync works, you can make a more educated decision on whether to enable it or not. It's also worth checking to see if your graphics package comes with additional enhancements; for example, Nvidia's Adaptive VSync aims to achieve the best of both worlds.
To Sync or Not to Sync
When used correctly, VSync can help smooth out issues and keep your graphics processor from running red-hot. When used incorrectly, it can needlessly harm your FPS and cause input lag without benefit. Now you know what VSync does and when to enable it.
Does VSync help with your issues? Let us know below!
This article was updated in May 2018.