How frame synchronisation prevents screen tearing in games
Screen tearing is a visual distortion in gaming where different frames appear on screen simultaneously, creating a jagged, split image. Although particularly common in PC gaming, the issue is caused by a mismatch between the speed at which a graphics card renders frames and the fixed refresh rate at which a monitor displays them. Fortunately, this once-problematic issue has been effectively solved through modern synchronisation technologies.
The problem occurs because GPUs render frames at variable rates whilst monitors refresh on fixed schedules, measured in hertz. When a GPU renders a new frame into the buffer before the monitor has finished displaying the previous one, both frames appear on screen at once, creating the characteristic tearing effect. Modern solutions like NVIDIA's G-Sync and AMD's FreeSync use variable refresh rate technology to synchronise the monitor's refresh rate with the GPU's frame output. Older V-Sync technology forces the GPU to wait between frames, which can introduce input lag and stuttering; the newer approaches offer superior performance without these trade-offs.
- Screen tearing happens when GPU and monitor speeds don't match, showing multiple frames simultaneously
- Variable refresh rate technologies like G-Sync and FreeSync effectively eliminate the problem
- Older V-Sync fix works but causes input lag and stuttering issues
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Screen tearing is a visual glitch in video games where the image appears to split horizontally, creating a jagged line across the screen. It happens when a graphics card and monitor get out of sync, and whilst it doesn't affect how the game plays, many players find it distracting to watch.
The problem comes from a timing mismatch: graphics cards produce new frames at unpredictable speeds depending on what's happening in the game, but monitors refresh their displays at a fixed rate, typically 60 to 144 times per second. If the graphics card finishes a new frame whilst the monitor is still showing the old one, both appear on screen simultaneously, creating the tearing effect.
Modern technologies like Nvidia's G-Sync and AMD's FreeSync solve this by letting the monitor's refresh rate adjust dynamically to match whatever speed the graphics card is producing frames. Older solutions like V-Sync forced the graphics card to slow down and wait, which could introduce other problems like delayed input response and stuttering.
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Originally published by Engadget as “What causes screen tearing and how can you fix it?”.