Docks & Monitors

4K or HDR won't engage on a TV

Fix a TV input stuck at 1080p/4K30 or refusing HDR — enable the per-input 'Enhanced/Deep Color' setting, use an Ultra High Speed cable, and know the HDMI 2.0 vs 2.1 bandwidth gates.

Problem summary

4K/HDR engaging depends on two gates that must both pass: bandwidth (the cable plus both ports' HDMI tier — 2.0 is 18 Gbps, 2.1 is 48 Gbps) and a per-input TV setting that opens the port to full bandwidth. The most common miss is that setting — Samsung's Input Signal Plus, LG's HDMI Deep Color, Sony's Enhanced format — which must be enabled on the specific input the source is plugged into, or the input runs in a reduced mode that caps at 4K30/8-bit with no HDR. And because HDMI 2.1 features are optional per device, the version label alone doesn't guarantee the bandwidth.

Operator snapshotEvidence first

First proof

Enable the per-input enhanced-bandwidth setting for the source's input.

Screen to open

TV settings → enable Input Signal Plus (Samsung) / HDMI Deep Color (LG) / Enhanced format (Sony) for the source's input.

Expected signal

Input Signal Plus / HDMI Deep Color / Enhanced format is on for that input.

Stop boundary

Stop assuming the label — verify and enable the actual capability.

Layer path

14K/HDR engaging depends on two gates that must both pass: bandwidth (the cable plus both ports' HDMI tier — 2.0 is 18 Gbps, 2.1 is 48 Gbps) and a per-input TV setting that opens the port to full bandwidth.

2The most common miss is that per-input setting — Samsung Input Signal Plus, LG HDMI Deep Color, Sony Enhanced format — which must be enabled on the exact input the source uses, or the input caps at 4K30/8-bit with no HDR.

3Cable tier matters: 4K60 needs at least High-Speed/Premium, and 4K120/8K needs certified Ultra High Speed (48 Gbps); a lesser cable silently caps the signal.

4Because HDMI 2.1/2.2 features are optional per device, the version label alone doesn't guarantee the bandwidth or feature — verify the actual spec.

Runbook

Step-by-step runbook

Start here. Do each check in order, compare it to the expected result, and stop when the evidence explains the failure or the safe stop point applies.

Enable the input setting

Check: Turn on the per-input enhanced-bandwidth setting.

Expected result: The input accepts full 4K/HDR.

If not: Set it on the exact input the source uses.

Set the source output

Check: Set 4K + HDR/Dolby Vision at the source.

Expected result: The source sends 4K/HDR.

If not: A capped source output won't engage 4K/HDR.

Match the cable

Check: Use a certified cable for the signal tier.

Expected result: The cable carries the full bandwidth.

If not: Swap to UHS for 4K120/8K.

Check the ports

Check: Confirm source and TV ports support the bandwidth.

Expected result: Both ports meet the tier.

If not: Move off a 2.0 port for 4K120/4:4:4.

Verify the feature is real

Check: Confirm the device actually supports the optional 2.1 feature.

Expected result: The needed feature/bandwidth is in the spec.

If not: 2.1 labeling doesn't guarantee it.

Safe stop: Stop assuming the label — verify and enable the actual capability.

Decision tree

If: Caps at 4K30 / 8-bit / no HDR

Then: The per-input enhanced setting is off.

Action: Enable Input Signal Plus / Deep Color / Enhanced format for that input.

If: No picture at 4K but fine at 1080p

Then: Cable or port can't carry the 4K bandwidth.

Action: Use a certified cable and a port that supports the tier.

If: HDR/Dolby Vision won't activate

Then: Source HDR output or the per-input setting is off.

Action: Enable HDR at the source and the enhanced input setting.

If: 'HDMI 2.1' device still won't do the feature

Then: The feature is optional and not implemented/enabled.

Action: Verify the device spec; enable the toggle if it exists.

Safe stop: Stop trusting the 2.1 label — confirm the actual capability.

If: Works direct but not through an AVR

Then: The AVR input doesn't pass the bandwidth.

Action: Use a true HDMI 2.1 AVR port or run source→TV direct.

Evidence

Evidence table

Symptom	Evidence to collect	Likely layer	Next action
Picture caps at 4K30/8-bit, no HDR option	The per-input enhanced setting state	Reduced 'Standard' input mode	Enable the enhanced-bandwidth setting for that input.
Black/no signal at 4K, fine at 1080p	Cable rating + port HDMI tier	Bandwidth gate (cable or port)	Certified cable + a port that supports the tier.
HDR/Dolby Vision won't turn on	Source HDR output + input setting	HDR not enabled end to end	Enable HDR at source + enhanced input setting.
'2.1' device lacks the feature	The device's actual feature list	Optional 2.1 feature not implemented	Verify the spec; don't trust the label.
Full 4K only when bypassing the AVR	AVR input HDMI tier	AVR port can't pass the bandwidth	Use a 2.1 AVR port or go direct.

Reference

Commands and settings paths

Enable the per-input enhanced setting

TV settings → enable Input Signal Plus (Samsung) / HDMI Deep Color (LG) / Enhanced format (Sony) for the source's input.

Where: On the TV menu, for the exact input

Expected: The input accepts full-bandwidth 4K/HDR.

Failure means: Left off, it caps at 4K30/8-bit with no HDR.

Safe next step: This is per-input — set it on the one the source uses.

Check the source output mode

Set the source's video output to 4K and enable HDR/Dolby Vision.

Where: On the source device's settings

Expected: The source sends a 4K/HDR signal.

Failure means: A 1080p/SDR output won't engage 4K/HDR on the TV.

Safe next step: Match the source output to the TV's capability.

Verify the cable/port tier

Use a certified Ultra High Speed cable on a port that supports the target (4K120/8K = 48 Gbps).

Where: At the HDMI connection

Expected: The link carries the full bandwidth.

Failure means: A lesser cable/port silently caps the signal.

Safe next step: Test with a short certified cable to isolate the cable.

Hardware boundary

Hardware and platform boundary

Change only when

Move to a certified Ultra High Speed cable and a confirmed HDMI 2.1 (48 Gbps) input when you need 4K120, 8K, or 4K60 4:4:4 — verify the feature, not the version label.

Evidence that matters

The per-input enhanced setting enabled, a certified cable for the tier, and ports that actually support the bandwidth/feature.

Evidence that does not matter

The HDMI version number on the box — 2.1/2.2 features are optional, so confirm the specific capability.

Avoid

Buying an Ultra96/8K cable for a 4K60 set, or blaming the TV before enabling the per-input enhanced setting.

Related tool/checklist

Use the linked tool when you need a guided plan from your exact symptoms instead of a static checklist.

USB-C dock & monitor setup planner

Last reviewed

2026-06-03 · Reviewed by HomeTechOps. Built from 2026-06 research verified against HDMI.org's bandwidth tiers/cable program and Sony's Enhanced-format support article. The operator differentiators are the per-input enhanced setting (the most common miss), the cable-tier gate, and the optional-2.1-features caveat.

Sources/assumptions

Assumes a 4K/HDR-capable source and TV connected over HDMI, with the goal of full 4K/HDR (and not a cap at 1080p/4K30/8-bit).
Bandwidth tiers and the optional-features caveat are from HDMI.org; the per-input 'Enhanced' setting name varies by brand (Samsung/LG/Sony examples) and is verified per maker.

Source-backed checks

HomeTechOps turns official docs and conservative safety rules into a shorter runbook. These links are the source trail for the page direction.

HDMI: HDMI 2.1 / 2.2 specification overviewUsed for the bandwidth tiers (2.0 = 18 Gbps, 2.1 = 48 Gbps, 2.2 = 96 Gbps), resolution/chroma support, and that 2.1/2.2 features (VRR/ALLM/4K120/eARC) are OPTIONAL per device.HDMI: Cables and the Ultra HDMI Cable Certification ProgramUsed for Ultra High Speed (up to 48 Gbps / 8K60 / 4K120) vs the newer Ultra96 (up to 96 Gbps) cable and the certified-cable requirement for full bandwidth and eARC.Sony Support: Enable the Enhanced HDMI signal format for 4K/HDRUsed for the per-input 'Enhanced format' setting (Sony) that must be enabled before a TV input accepts full-bandwidth 4K/HDR — the most common 4K-won't-engage miss.

Diagnostic rule

1. Check the simplest signal first.
2. Change one thing at a time.
3. Avoid unsafe electrical or data-loss steps.
4. Stop when the evidence says the risk moved.

FAQ

My TV caps at 4K30 / 8-bit / no HDR — what's the fix?

Enable the per-input enhanced-bandwidth setting. It's called Input Signal Plus (Samsung), HDMI Deep Color / Ultra HD Deep Color (LG), or Enhanced format (Sony), and it must be turned on for the exact HDMI input the source uses — otherwise the input runs in a reduced 'Standard' mode that caps at 4K30/8-bit with no HDR. This is the single most common 4K-won't-engage miss. See Sony's Enhanced format article for one brand's path.

Do I need a special HDMI cable for 4K?

For 4K60 you need at least a High-Speed/Premium cable; for 4K120 or 8K you need a certified Ultra High Speed HDMI cable (up to 48 Gbps). A lesser cable silently caps resolution/refresh or causes dropouts. Use a certified cable and test with a short known-good one to rule the cable in or out.

My device says 'HDMI 2.1' but features still don't work — why?

Because HDMI 2.1 (and 2.2) features — the full 48/96 Gbps bandwidth, VRR, ALLM, 4K120, eARC — are optional per the spec. A device labeled '2.1' is not guaranteed to support any specific feature or the full bandwidth, so verify the actual feature/bandwidth in the device's spec rather than trusting the version number.