What is Variable Refresh Rate (VRR) and how does G-Sync/FreeSync work?

Variable Refresh Rate (VRR) dynamically synchronizes your monitor's refresh rate to the instantaneous frame rate output of your graphics card (GPU). This eliminates horizontal screen tearing and minimizes stutter without the high latency penalty of traditional V-Sync.

What is Low Framerate Compensation (LFC)?

LFC automatically multiplies frame delivery (e.g., displaying 30 FPS at 60Hz or 120Hz) when the game frame rate drops below the monitor's minimum native VRR range (typically < 48Hz), preventing stutter and tearing at low frame rates.

How do I set optimal G-Sync/FreeSync frame rate caps?

To stay strictly within your display's VRR operating window, set a frame rate cap 3 to 4 FPS below your monitor's maximum refresh rate (e.g. cap at 141 FPS on a 144Hz monitor, or 237 FPS on a 240Hz monitor) and enable V-Sync in your GPU driver control panel.

VESA ADAPTIVE-SYNC & HIGH-REFRESH PACING

VRR, G-Sync & FreeSync Stutter Test

Q: How do I set optimal G-Sync/FreeSync frame rate caps?

To stay strictly within your display's VRR operating window, set a frame rate cap 3 to 4 FPS below your monitor's maximum refresh rate (e.g. cap at 141 FPS on a 144Hz monitor, or 237 FPS on a 240Hz monitor) and enable V-Sync in your GPU driver control panel.

Modulate synthetic frame rates across your display's VRR window (48Hz to 540Hz+), evaluate LFC (Low Framerate Compensation) doubling behavior, measure micro-stutter, and inspect visual tear lines.

WARNING: PHOTOSENSITIVE SEIZURE & FLICKER HAZARD

A small percentage of individuals may experience epileptic seizures or photosensitive reactions when exposed to flashing lights, high-contrast strobing, or rapidly moving visual patterns. In compliance with WCAG 2.1 Success Criterion 2.3.1 (Three Flashes or Below Threshold), Display Test Online limits default strobing animations. However, dynamic visual tests inherently involve rapid refresh intervals.

Discontinue use immediately and consult a physician if you experience dizziness, altered vision, twitching, loss of awareness, or disorientation while running tests.

VRR (G-Sync / FreeSync) Stutter & Tearing Engine

Check your display's Variable Refresh Rate synchronization. The vertical sweep bars oscillate speed dynamically across frame intervals. Any stuttering, tearing, or overdrive overshoot reveals synchronization failures.

FPS Telemetry0.0 Hz

Frame Interval0.00 ms

Sync Loss Counts0

VESA ADAPTIVE-SYNC METHODOLOGY

Variable Refresh Rate (VRR) Mechanics & LFC Threshold Physics

Variable Refresh Rate (VRR) technologies—including NVIDIA G-Sync, AMD FreeSync, and VESA Adaptive-Sync—dynamically match the monitor's physical refresh rate to the GPU's instantaneous frame rendering pace. When GPU rendering latency fluctuates, fixed-refresh displays trigger either visual tearing (with VSync OFF) or periodic stutter (with VSync ON).

VRR Window Range48 Hz to Max Refresh

The hardware range within which VSync timing adjusts dynamically to match GPU output.

LFC ThresholdFrame Doubling Below 48Hz

When FPS drops below the minimum VRR bound (e.g. 36 FPS), LFC repeats frames (72 Hz) to prevent stutter.

VRR Gamma FlickerOLED Voltage Sensitivity

Rapid VSync frame time oscillations can alter sub-pixel pixel charging times, causing subtle brightness shifts on OLED panels.

Browser & OS Color Management Limitations

Software-based visual evaluation patterns are subject to Web browser color space mapping (sRGB / Display P3), operating system display scaling, ICC profile overrides, and GPU driver settings. While Display Test Online utilizes hardware-accelerated WebGL 2.0 rendering pipelines, browser-based tests cannot fully replace physical hardware colorimeters or spectrophotometers (e.g., Calbrite Display Plus HL, X-Rite i1Display Pro) for color-critical prepress workflows.

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Dead Pixel Test Sub-Pixel Analyzer OLED Uniformity VRR Sync Engine OLED Burn-In Risk HDR Brightness PPI Calculator Color Gamut & ICC

VRR Frame Pacing

rAF Microsecond Jitter

540Hz Sweep

Current: 240 HzJitter σ: 0.08 ms

PASS

LFC Active

Low Framerate Compensation

ACTIVE

Target Range48 Hz - 240 Hz

LFC Mode2x Multiplier

VRR Sweep Range

Oscillation Tuning

Controls

Sweep Frequency Bounds

Inject Synthetic Stutter Spike

Shortcuts

Keyboard Navigation

Hotkeys

F

Toggle Fullscreen Mode

S

Inject Synthetic Stutter

Space

Pause / Resume Oscillation

TV users can navigate with D-Pad & Remote arrow keys

VESA Adaptive-Sync

G-Sync & FreeSync Specs

VESA Standards

Standard Citations

VESA Adaptive-SyncSection 3.2

Mandates 48-144Hz dynamic timing sync with microsecond frame dispatch.

Monitor OSD Calibration

Set FPS cap 3-4 FPS below native refresh rate (e.g. 237 FPS on 240Hz) to prevent VSync input latency penalties.