Screen Tearing & V-Sync Technologies
Buffer swaps, horizontal tear lines, input latency trade-offs, and adaptive sync.
Screen tearing is a visual distortion where a display shows information from multiple frames in a single screen refresh, appearing as a horizontal seam or 'tear' across the image.
Why It Matters
Screen tearing ruins visual immersion in fast-paced motion and games. While traditional V-Sync eliminates tearing, it introduces noticeable mouse latency and stutter when frame rates dip below your monitor refresh rate.
What Users Should Look For
- Horizontal split lines where the top half of the screen does not align with the bottom half during camera pans
- Multiple horizontal tear seams cascading down the display during rapid motion
- Stutter and mouse latency spikes when frame rate fluctuates below native refresh rate
- Pacing judder when watching 24 FPS video on a 60Hz display (3:2 pulldown judder)
How to Test This Parameter
- 1Run the Screen Tearing Test in Screen Tester to watch high-speed vertical bars sweep across the display
- 2Run the VRR Visual Inspection test under dynamic workloads to observe frame pacing stability
- 3Verify whether horizontal tearlines appear when sweeping test objects at maximum browser framerates
Technical Testing Boundaries & Methodology
Screen Tester emphasizes transparency: we clearly delineate between what web browser engines can mathematically inspect versus what requires specialized physical laboratory probes.
- ✓High-velocity vertical bar animation loops timed against the browser compositor
- ✓Animation frame delivery intervals via `requestAnimationFrame`
- ✓Visual tearing seams visible to user inspection across full-screen canvas viewports
- ✕GPU driver frame buffer swapchain latency in milliseconds
- ✕Hardware VESA Adaptive-Sync or NVIDIA G-Sync chip hardware handshake packets
- ✕Direct mouse-to-display end-to-end system input latency
Why Screen Tearing Happens
Monitors draw images line-by-line from top to bottom at a fixed refresh rate (e.g., 60 or 144 times per second).
Your graphics card renders frames to an internal buffer. Without synchronization, the GPU copies a newly finished frame into the display memory mid-scanout. The monitor draws the top half from the old frame and the bottom half from the new frame, creating a visible horizontal split.
Common Causes
- •V-Sync disabled while running games at frame rates that do not match the monitor refresh rate
- •Variable Refresh Rate (G-Sync / FreeSync) not enabled in both GPU drivers and monitor OSD
- •Game frame rate exceeding the maximum VRR range of the monitor (e.g., rendering 180 FPS on a 144Hz screen)
- •Windowed mode desktop composition conflicts between multiple monitors with mismatched refresh rates
Recommended Next Steps
- →Enable G-Sync or FreeSync in your GPU control panel and monitor OSD
- →When using VRR, enable V-Sync in the GPU driver control panel and cap your frame rate 3 FPS below your max Hz (e.g., cap at 141 FPS on a 144Hz monitor) to stay within the VRR window
- →If you do not have a VRR monitor, use FastSync (NVIDIA) or Enhanced Sync (AMD) to reduce tearing with minimal latency
Frequently Asked Questions
Does V-Sync add input lag?
Yes. Traditional double-buffered V-Sync forces the GPU to wait until the monitor finishes its refresh cycle before rendering the next frame. This backpressure can add 16 to 50 milliseconds of input latency.
Why should I cap my FPS 3 below my refresh rate with G-Sync?
If your FPS reaches or exceeds your monitor's maximum refresh rate (e.g., 144 FPS on 144Hz), G-Sync disengages and reverts to standard V-Sync (adding lag) or no sync (causing tearing). A 3 FPS limiter keeps you permanently inside the tear-free G-Sync window.