LG OLED G3/G4 PS5 Says 120 Hz Unsupported: Complete Signal Check

Quick Answer

The G3/G4 can accept 4K120 from PS5, but the console does not keep its menu at 120 Hz merely because 120 Hz Output is set to Automatic. PlayStation states that 120 Hz output applies to games that support a 120-fps mode. First open PS5 Settings → Screen and Video → Video Output → Video Output Information and inspect the capability reported by the complete HDMI chain. Then launch a confirmed 120 Hz game and enable its Performance/120 Hz mode if required.

Connect PS5 directly to a G3/G4 HDMI input using the PS5-supplied cable or a certified Ultra High Speed cable. Enable LG HDMI Deep Color/4K for that input and Game Optimizer. If direct works but AVR/soundbar routing does not, the intermediary, its selected ports, cable pair or video mode is limiting the chain. Add VRR and HDR only after stable 4K120. Do not enable the G4's PC-oriented 144 Hz option for PS5; PS5's target here is 120 Hz.

Symptoms: Unsupported or Simply Inactive?

PS5 menu displays 60 Hz: often normal; a supported game must request 120 Hz.

Video Output Information omits 120 Hz: chain capability/setting issue.

120 Hz appears at 1080p but not 4K: cable, Deep Color, intermediary or bandwidth branch.

Direct TV works, AVR path does not: AVR port/mode/cables/firmware limitation.

Black screen only when game switches to 120 Hz: handshake/bandwidth, not proof of unsupported panel.

120 Hz works but VRR says unsupported: test VRR separately; features are related but not identical.

Owners report “unsupported” after routing through receivers, using incorrect AVR ports, or mode changes; others see black screens that recover after direct connection or format toggles. These reports are symptom evidence, not a reason to replace a working panel.

Causes and Unique Diagnostic Tree

Branch 1: Does the game actually support 120 Hz?

Verify the game's official documentation and current patch. In-game settings may require Performance Mode, 120 Hz mode or reduced graphics quality. PS5 system Game Presets → Performance Mode can influence supported titles, but does not force unsupported software to render 120 fps.

Launch the title and then reopen Video Output Information or the LG Game Dashboard. Judge active refresh during gameplay, not the dashboard/home screen. A game's frame rate can also vary below 120 while the HDMI output remains a 120 Hz container.

Branch 2: What does PS5 report for the connected display?

Set Resolution Automatic, 120 Hz Output Automatic and initially VRR Off. Use Test 1440p Output if diagnosing 1440p; PlayStation's test explicitly checks SDR/HDR 60/120 and VRR combinations. For 4K, inspect frequencies and color formats in Video Output Information.

If no picture, boot PS5 Safe Mode using PlayStation's official procedure and choose a conservative resolution/video-output change. Do not repeatedly force shutdown during storage activity. Update PS5 system software officially.

Branch 3: Is the TV input configured for high bandwidth?

On the exact HDMI input, enable LG HDMI Deep Color/4K and Game Optimizer/ALLM. Settings are input-specific. Power the PS5 down normally, reconnect, then restart so capabilities renegotiate. Try another G3/G4 HDMI input to exclude one port/configuration.

Do not copy PC chroma settings or enable 144 Hz Boost for PS5. G4 specifications list 4K120 high-frame-rate support and PS5 officially supports 4K120. Keep aspect ratio/Just Scan normal and avoid service-menu EDID edits.

Branch 4: Can cable and direct topology carry it?

Use the cable included with PS5 or HDMI-certified Ultra High Speed cable. Keep length practical, avoid tight bends and test another certified cable. HDMI.org explains certification categories; marketing text such as “8K” alone is not verification.

Connect PS5 straight to TV. If 4K120 now appears, the original AVR, soundbar input, switch, wall plate, extender or second cable is causal in the path. Both cables around an AVR must support the mode.

Branch 5: Does the AVR/soundbar support the selected route?

Consult its manual for which inputs/outputs support 4K120, VRR, HDR and enhanced/8K mode. Many receivers support high bandwidth only on specific sockets or after enabling Enhanced/8K Signal Format. Update firmware officially and test with video processing/scaling disabled.

eARC does not require routing PS5 video through the soundbar/AVR: connect PS5 to TV and return audio through eARC when supported. This is a valid topology test and often the simplest stable arrangement.

Branch 6: Does VRR or HDR trigger failure?

After 4K120 SDR works, enable HDR, then VRR. PlayStation allows VRR for supported games and an option to apply it to unsupported games; leave the latter off during diagnosis. If only VRR fails, confirm LG VRR/Game Optimizer state and retest direct.

Brief blackness during mode switch can be HDMI resync. Repeated dropouts during steady play suggest cable/link instability. Capture PS5 output info and LG dashboard rather than lowering unrelated brightness controls.

Step-by-Step Safe Fix

Confirm the title/patch supports 120 Hz and enable its Performance/120 mode.

Check PS5 Video Output Information during gameplay.

Set Resolution and 120 Hz Output to Automatic; VRR Off for baseline.

Enable LG HDMI Deep Color/4K and Game Optimizer on the active port.

Use PS5 cable or certified Ultra High Speed cable directly to TV.

Try another TV port and restart both devices normally.

Establish 4K120 SDR, then add HDR and VRR individually.

If using AVR, verify exact enhanced 4K120 ports and both cables.

Prefer PS5-to-TV plus eARC audio when intermediary video is limiting.

Update officially; contact PlayStation/LG if direct conservative tests still disagree.

Do not hot-plug repeatedly, force 144 Hz, use EDID emulators, install unofficial firmware or service-menu HDMI changes. Preserve screenshots before resets.