G-Sync, FreeSync, and Variable Refresh Rate: What VRR Actually Does for GPU Output

Screen tearing happens when the GPU delivers a new frame partway through a monitor's refresh scan, producing a visible horizontal split. V-Sync eliminates tearing by holding frames until the display is ready, but adds a full frame of latency and causes stutter when frame rate dips below refresh rate. Variable refresh rate technologies eliminate both problems by making the monitor wait for the GPU instead.

What VRR solves at the signal level

A fixed refresh rate monitor completes its panel scan at a rigid interval regardless of what the GPU has finished rendering. At 144 Hz, one scan completes every 6.94 ms. If the GPU delivers frame N at 2 ms and frame N+1 at 9 ms, the monitor's fixed-interval scan picks up part of frame N and part of frame N+1 in the same pass: a horizontal tear line across the image. V-Sync queues frames to align with scan starts, eliminating tearing but adding a full frame period of latency and causing visible microstutter whenever frame timing is irregular.

A variable refresh rate monitor uses an adaptive synchronization signal. Instead of scanning at a fixed interval, the panel holds after its current frame and waits for the GPU to signal frame completion, then scans the new frame. The monitor's effective refresh rate at any moment matches the GPU's current output rate. Tearing cannot occur because a new scan never begins before a complete frame is ready, and no frames are queued in a buffer, so input latency remains low.

G-Sync, FreeSync, and HDMI VRR compared

G-Sync hardware module vs G-Sync Compatible

Original G-Sync certification requires a proprietary NVIDIA scalar module embedded in the monitor. This module typically extends the operating VRR range down to 1 Hz, allows the monitor to sustain adaptive sync at extremely low frame rates without artifacts, and includes NVIDIA's own overdrive implementation tuned to work at variable refresh intervals. G-Sync module panels command a significant price premium.

G-Sync Compatible is NVIDIA's designation for VESA Adaptive-Sync monitors that NVIDIA has tested and confirmed to operate without significant flicker, blanking, or visual artifact when connected to an NVIDIA GPU with adaptive sync enabled in the driver. Hundreds of monitors carry this designation. For gaming at frame rates comfortably within the panel's VRR range, G-Sync Compatible monitors function identically to native G-Sync for the majority of users.

VRR operating range and low framerate compensation

Every VRR monitor has a minimum and maximum refresh rate between which adaptive synchronization operates. A typical gaming display might support 48 to 165 Hz VRR. When the GPU's frame rate drops below the minimum (below 48 fps here), the monitor exits the VRR window and either tears like a fixed-refresh panel or locks to a fixed sub-multiple.

Low Framerate Compensation (LFC) addresses this problem by doubling (or multiplying) each frame's display time to keep the effective refresh rate above the VRR minimum. LFC only activates when the maximum VRR rate is at least twice the minimum: a 48 to 165 Hz panel supports LFC because 165 / 48 = 3.4. A 90 to 165 Hz panel does not. In practice, FreeSync Premium Pro mandates LFC support, making it a meaningful certification distinction for users whose frame rates dip below 60 fps in demanding titles.

Overdrive interaction with variable refresh timing

Panel overdrive applies a voltage boost to pixels to accelerate transition time and reduce ghosting. Calibrated for a fixed refresh interval, the boost level is tuned to clear pixel transitions within one frame period. When the refresh interval varies under VRR, overdrive tuned for maximum rate (6.94 ms at 144 Hz) becomes excessive at lower rates (16.7 ms at 60 Hz), producing inverse ghosting: a bright halo artifact trailing behind moving objects.

Most VRR-capable monitors include an adjustable overdrive setting. Set overdrive to medium or low when running VRR and test with a fast pixel transition sequence at varying frame rates. The correct setting eliminates inverse ghosting without allowing significant standard ghosting at the panel's maximum refresh rate.

When VRR has the most practical impact

VRR is most perceptible and valuable in the 50 to 100 fps range. At frame rates consistently above the monitor's maximum refresh rate, the GPU is capped by the display ceiling and VRR range is never entered. At frame rates consistently below the VRR minimum without LFC, adaptive sync disengages. The scenarios where VRR eliminates the most annoyance are open-world titles where GPU load varies heavily by scene complexity, producing frame rate swings between 55 and 95 fps through the same session. This is precisely the range where tearing is most visible and where V-Sync stutter is most disruptive, and where VRR produces a clean, low-latency image without compromise.