LG OLED C4 VRR Flicker in Dark Scenes: Frame-Time and Gamma Fixes

Quick Answer

First prove that the C4 is flickering without losing the HDMI signal: the picture remains present, sound continues, and dark gray areas pulse as frame rate changes. Display a frame-time graph, cap the game at a frame rate the GPU can sustain, and compare the same dark scene with VRR enabled and disabled. If a stable cap removes the pulsing, uneven frame delivery—not the cable—is exposing near-black VRR gamma variation.

LG specifies a 40–144 Hz VRR range. Below it, low-framerate compensation (LFC) may repeat frames to keep refresh in range. Boundary crossings, shader stalls, and frame-time spikes can visibly change dark tones. No universal setting removes this OLED behavior while preserving every VRR benefit.

Symptoms: VRR Gamma Flicker or Signal Dropout?

Choose a reproducible scene with dark gray walls, fog, shadows, or a paused menu. Pure black pixels are off, so the effect is usually clearest just above black.

Near-black areas pulse between slightly lighter and darker shades: typical VRR luminance/gamma behavior.

The entire screen goes black and the TV reports No Signal: troubleshoot HDMI synchronization, not this guide.

A loading screen flickers while gameplay is stable: loading-time frame spikes or LFC transitions are likely.

The effect stops immediately when VRR is disabled: strong evidence that variable timing is required for the symptom.

Flicker remains at fixed refresh in webOS menus: VRR cannot explain it; inspect the source image or panel.

Only one corner or fixed band flashes: this is not the usual whole-tone VRR response and may need service.

Owners report dark-scene pulsing and changed severity after swapping GPUs despite similar average fps. This implicates frame delivery and content, not every panel.

Causes and Frame-Time Diagnostic Tree

Branch 1: Does disabling VRR remove the effect?

Keep resolution, refresh, HDR, picture mode, game scene, and camera position unchanged. Disable G-SYNC/FreeSync or the console VRR option and replay the scene at fixed refresh. Do not change brightness or Fine Tune Dark Areas during this A/B test.

If pulsing disappears, VRR timing is involved. Otherwise inspect dithering, film grain, effects, HDR mapping, or the panel. Test cables only for sparkles, corruption, or sync loss.

Branch 2: Is average fps hiding poor frame time?

An “80 fps” counter can conceal alternating short and long frames. Use the game's graph, NVIDIA FrameView, AMD metrics, or another reputable frame-time capture. Look for spikes when traversal, shader compilation, autosaves, menus, or frame generation changes state. Frame time is the duration of each rendered frame; consistent delivery matters more here than a high arithmetic average.

Reduce settings causing unstable load, often ray tracing, crowd density, or aggressive frame generation. Use only supported shader-cache workflows and retest after patches.

Branch 3: Does a sustainable fps cap reduce flicker?

Choose a cap the system can hold in the problematic area, not in an easy benchmark. For a game fluctuating from 70 to 105 fps, a stable 72 or 80 may look cleaner than an uncapped output. Use one limiter only: in-game, GPU driver, or a trusted external tool. Multiple limiters can interact and worsen pacing.

Keep the cap below the active maximum. AMD recommends V-Sync or a cap when output exceeds refresh; NVIDIA provides G-SYNC-compatible per-game controls. Recheck the graph because a configured cap may still pace unevenly.

Branch 4: Is the game crossing the fps floor or invoking LFC?

LG lists the C4 VRR range from 40 Hz. AMD explains that LFC duplicates frames below a display's minimum—for example, a low frame rate can be shown at a multiple within range. The exact behavior depends on GPU, API, and active VRR path.

Watch for flicker around the lower boundary. Stay comfortably above it, then compare fixed refresh. If the first is cleaner, crossings mattered. Do not alter the range with unofficial EDID overrides.

Branch 5: Is frame generation changing cadence?

Test native rendering without frame generation, then enable it without changing anything else. Generated fps can look high while base-frame cadence or UI transitions remain uneven. If flicker increases only with generation, choose a steadier base frame rate, a lower graphics preset, or disable generation for that title. Upscaling itself is not the same as frame generation, so test them separately.

Branch 6: Is the source stable but dark gamma still distracting?

Open Game Optimizer → Fine Tune Dark Areas while VRR is active. Small adjustments can make the visible near-black shift less objectionable, but this control changes shadow rendering globally and cannot track every instantaneous frame time. Use a familiar black-level pattern and game scene; stop before blacks are crushed or raised.

Keep SDR and HDR preferences separate. Random brightness, range mismatches, or service-menu values merely hide flicker by destroying shadow detail.

Step-by-Step Safe Mitigation

Record a reference. Note C4 firmware, GPU/console version, active VRR type, refresh ceiling, HDR state, fps range, and exact scene.

Confirm signal lock. Distinguish gray pulsing from No Signal, blackouts, or colored corruption.

Run a VRR-off control. Preserve every other setting. If flicker remains, leave this workflow and diagnose the source/panel.

Capture frame time. Identify spikes, loading events, and oscillation near the lower or upper VRR boundary.

Stabilize workload. Reduce the limiting graphics/CPU setting and test without frame generation.

Apply one sustainable cap. Select a value held in the worst scene, below the active maximum, then verify the graph.

Use Fine Tune Dark Areas sparingly. Make the smallest useful change and verify that intended shadow detail remains visible.

On consoles, compare the game's quality and performance modes. A stable 60 or 120 fps target may flicker less than a mode with broad fluctuations. If one title's menu flickers but gameplay does not, disabling VRR globally may cost more smoothness than it gains; use a per-title option when the platform provides one.

Limitations, Cautions, and Service Criteria

VRR solves tearing by matching refresh to GPU delivery; NVIDIA and AMD both describe that synchronization benefit. It cannot make an inconsistent renderer produce consistent frame times. Conversely, V-Sync or fixed refresh can remove the variable-gamma trigger but may introduce tearing, latency, or judder depending on configuration. Choose the compromise per title.

Do not disable OLED protection, run pixel cleaning, modify EDID, or enter the service menu. Avoid “fixes” that crush near-black levels until the flicker becomes invisible. Fine Tune Dark Areas is a mitigation, not panel recalibration, and another owner's number may be wrong for your signal.

Contact LG if flicker appears in internal webOS screens, at fixed refresh with all HDMI devices removed, or as localized flashing independent of image content. Contact the GPU/game vendor when a repeatable driver or title update changes frame-time behavior. A second C4 may differ slightly, but panel replacement cannot guarantee elimination of technology-level VRR gamma variation.