What causes screen tearing and how can you fix it?

Most gamers have experienced the dreaded phenomenon of screen tearing. One moment you’re fighting enemies in a fantasy world, and the next you’re staring at a crazy patchwork of imagery. The torso of your avatar in the game is separated from its legs and head, and the path in front of you is also torn.

This is called screen tearing, which is a collection of visual artifacts that can plague your gaming session. While much more commonly encountered with PC gaming, it can sometimes be a problem for console gamers as well. The good news is that we not only know exactly why screen tearing happens, but also how to fix it.

The issue is mainly caused by a mismatch between the speed at which your computer’s hardware renders frames of video and the rate at which your screen can display them to you. But thanks to a combination of technologies that help coordinate frames between your graphics card and your monitor, screen tearing is no longer the scourge it once was.

What causes screen tearing is pretty simple: your GPU delivers frames at a different rate than your monitor displays them. Think of the image rendering pipeline as a two-person assembly line where your GPU “hands” video frames to your monitor. The problem is that many GPUs are not connected to the speed of the monitor. Sometimes a GPU will overclock the monitor, rendering up to hundreds more frames per second than the monitor can display. Other times, your GPU may render very few frames when a game puts a heavy load on it.

Normally, a monitor must refresh on a fixed schedule, just as the person at the end of an assembly line must drop the last item they were handed before a new one is accepted. The speed at which it can do this each second, measured in hertz, is referred to as the refresh rate. The output of the GPU is measured in frames per second (fps).

On basic monitors, refreshes happen 60 times every second. Gaming-focused monitors offer higher refresh rates such as 144Hz or higher – 240Hz is increasingly common on the midrange and even 1,000Hz monitors are now on the market. As refresh cycles become faster, they become more and more imperceptible to the untrained eye.

But you can easily see what happens when the GPU puts a new frame into the buffer before the monitor has scanned the previous one. This can display parts of both frames on your screen at once, as the monitor scans the frame buffer from top to bottom.

The incongruities between those frames are the dreaded tear screen effect, where, for example, the top of a tree appears on the side of its trunk. These slices occur because two frames of video simultaneously occupy different horizontal bands of the screen.

The good news is that screen tearing is essentially a solved problem. Thanks to variable refresh rate technology, monitors can synchronize their refresh rates with the frame rate of a graphics card, effectively eliminating the possibility of the monitor displaying two frames at once. The big names in VRR are NVIDIA G-Sync and AMD FreeSync.

Neither of those should be confused with V-Sync, another widely available technology designed to prevent screen flickering in video games. V-Sync forces the GPU to wait until the monitor is ready before transferring a new frame, instead of producing new frames as fast as they can. To continue using the assembly line analogy, V-Sync tells the person at the beginning of the line the exact moment to pass items to the second worker.

But this can cause its own problems. Since each frame is now waiting for its turn, V-Sync can cause input lag. And if the frame rate drops for a moment, the monitor repeats the frames, causing stuttering, which is just as annoying as screen tearing. However, that doesn’t mean you should use V-Sync.

G-Sync and FreeSync take a different, more effective approach: variable refresh rates. With G-Sync, traditionally a hardware module within officially supported monitors coordinates with the GPU. It binds the refresh rate of the monitor to that of the GPU, waiting to draw the next frame until the GPU finishes. Meanwhile, newer “G-Sync Compatible” monitors can use this functionality without the special hardware. (The next generation of G-Sync will also address motion blur through a feature called Pulsar.)

FreeSync achieves the same goal without a hardware module by using the VESA Adaptive-Sync protocol. In both cases, the VRR is a bit like adding a foreman to the assembly line that makes sure the worker at the end of the line adjusts their pace to match what the one at the beginning is doing.

You may have noticed that the VRR was designed with the exact problem it was designed to solve. If screen tearing is caused by desynchronization between a monitor and GPU, and if VRR simply tells the monitor how fast the GPU is working at any given moment, we still haven’t considered what happens when the GPU exceeds the monitor’s top refresh rate. And you are right; VRR cannot make a monitor faster than it already is. It only works well in that monitor’s native refresh window, outside of which visual tearing still occurs.

Therefore, it is recommended to use both V-Sync and G-Sync or FreeSync at the same time. While the VRR works to keep frame rates synchronized between the GPU and the monitor, V-Sync ensures that the GPU’s frame rate output cannot exceed the monitor’s capabilities by keeping it within the VRR window. However, it’s best to disable V-Sync from your computer’s global NVIDIA or AMD graphics settings, rather than using the in-game setting, and set the in-game frame rate cap to just slightly below your monitor’s top refresh rate. For example, games on a 240Hz monitor should be completed at around 235 fps. In addition to preventing screen tearing, this also helps stabilize your frame rates for smoother gaming.