What is vsync?

VSync Explained

VSync, short for Vertical Synchronization, is a graphics technology that synchronizes the frame rate of a video game or application with the refresh rate of the monitor. This synchronization aims to reduce or eliminate screen tearing.

• Screen Tearing: Occurs when the graphics card outputs frames faster than the monitor can display them. This results in the top and bottom portions of the screen displaying different frames simultaneously, creating a visible "tear" line.

• How it Works: VSync forces the graphics card to wait until the monitor finishes displaying a frame before starting to render the next one. This ensures that only complete frames are displayed, preventing tearing.

• Benefits:

  • Eliminates or reduces screen tearing.
  • Can smooth out frame rate fluctuations, especially when the frame rate is close to the monitor's refresh rate.
  • Can reduce GPU load and power consumption in certain situations, especially when the application renders frames significantly faster than the monitor's refresh rate.

• Drawbacks:

  • Input Lag: Can introduce input lag because the graphics card might have to wait before sending a frame. This delay can be noticeable, especially in fast-paced games.
  • Frame Rate Limitations: If the graphics card cannot consistently maintain a frame rate at or above the monitor's refresh rate, VSync will force the frame rate to drop to a multiple of the refresh rate (e.g., from 60 FPS to 30 FPS if the refresh rate is 60 Hz). This can cause noticeable stuttering.

• Alternatives to VSync:

  • Adaptive VSync: A NVIDIA technology that dynamically enables or disables VSync based on the frame rate. It enables VSync when the frame rate is above the refresh rate to prevent tearing and disables it when the frame rate drops below the refresh rate to avoid the performance hit.
  • FreeSync: An AMD technology that dynamically adjusts the monitor's refresh rate to match the frame rate output by the graphics card, eliminating tearing and reducing stuttering.
  • G-Sync: An NVIDIA technology that, like FreeSync, adjusts the monitor's refresh rate dynamically to match the GPU's frame rate. Requires a G-Sync compatible monitor.

• When to Use VSync: VSync is generally useful if you experience screen tearing and your graphics card can maintain a frame rate close to your monitor's refresh rate. If input lag is a major concern, or if your frame rate frequently dips below the refresh rate, alternatives like Adaptive VSync, FreeSync, or G-Sync might be preferable or disabling VSync altogether.