FIELD GUIDESource-led reference
Port & Cable

symptom

Resolution works, but high refresh, HDR or VRR is missing

Write the whole requested mode: resolution, refresh, color depth/chroma, HDR and VRR. Find the first stage whose exact documented table does not support it; a connector version or '4K' label is insufficient.

Applies to: Source-scoped examples: Elgato 4K X codec/DSC limits, Dell WD22TB4 link cases, Dell U2720Q USB-C prioritization.

video
Source output → cable/adapter → dock or capture stage → chosen monitor input
data
USB data sharing can change the available display path; USB capture has its own codec/rate.
power
Keep powered converter/dock/display requirements separate.
Functional path diagram. Arrows show the stated role and direction; they do not report an observed connection.

What the path requires

  • Record exact host/GPU/OS, port and monitor input.
  • Read the relevant table row, including lane/link and DSC conditions.
  • Use a manufacturer-supported baseline mode for direct-path comparison.

DSC is a path condition

Display Stream Compression support must apply to the actual source, intermediate stage and input. A dock row using DSC is not evidence that another adapter or capture device accepts a DSC signal.

Elgato Game Capture 4K X — Supported Resolutions and Frame Rates · Dell Thunderbolt Dock WD22TB4 User Guide — Display resolution table

Worked documentary examples

4K60 NV12 capture on 5Gbps USB

Documented outcome: Limiting stage identified by the published capture table

  • Elgato 4K X, NV12 8-bit 4:2:0, 3840×2160; TV picture may remain 60Hz.
  1. Read the USB codec table: 30fps is listed on 5Gbps, 60fps on 10Gbps.
  2. Check the negotiated USB path and app mode.
  3. Do not blame HDMI passthrough for a USB capture-format limit.
Elgato Game Capture 4K X — Supported Resolutions and Frame Rates

Follow the observation

Read the result before moving to the next branch. Leave unavailable evidence unknown.

1. Requested tuple is absent from one stage's table

What it supports: The exact requested mode is not documented for that path.

Next action: Use a documented mode or investigate a differently specified path.

Stop / escalation: Do not invent a timing override.

2. 4K X passthrough works but capture is black with DSC

What it supports: Elgato excludes DSC capture; display success does not establish capture support.

Next action: Use the vendor-directed lower resolution/refresh comparison, then check capture codec and USB rate.

Stop / escalation: Do not bypass protected-content controls.

3. Dock table assumes HBR3/DSC but actual host link is unknown

What it supports: Mode support is unresolved, not a proven cable failure.

Next action: Identify host port/link and exact selected dock outputs before applying the row.

Stop / escalation: Do not claim a universal bandwidth verdict.

4. U2720Q changes behavior when USB-C priority changes

What it supports: Its documented video/data allocation changed.

Next action: Read the exact High Resolution/High Data Speed setting and required data task; save work before altering the connection.

Stop / escalation: Do not transfer this model's setting to every USB-C monitor.

Your next useful observation

Record each stage's supported tuple and the actual offered mode before changing one component.

Keep these limits

  • No mode, HDR, chroma, VRR or bandwidth measurement.
Source documents, revisions and inspection methods

Elgato Game Capture 4K X — Supported Resolutions and Frame Rates

Elgato · Updated 2026-05-21

Input and Capture Resolution Matrix; Detailed Capture Codec Specifications

Inspected 2026-10-23 by public_page. Primary HTML tables inspected; AI-assisted source reading, no independent human review or hardware validation.

Capture and passthrough are different paths, with software and USB-link qualifications.

Read the original source

Dell Thunderbolt Dock WD22TB4 User Guide — Display resolution table

Dell · Online revision unavailable; retrieved page redirected to fr-be with English technical tables

HBR2/HBR3 USB-C and Thunderbolt tables; EDID note; HDMI/MFDP exclusion

Inspected 2026-10-23 by public_page. Primary HTML body and relevant table inspected; AI-assisted source reading, no independent human review or hardware validation.

Exact dock link/port selection, DSC and EDID qualifications.

Read the original source

Dell U2720Q/U2720QM User’s Guide

Dell · 2020-01 Rev. A00

USB-C Prioritization; Plug-and-Play; Preset Display Modes

Inspected 2026-10-23 by public_pdf_text. Primary PDF text and relevant table inspected; AI-assisted source reading, no independent human review or hardware validation.

Exact U2720Q modes and USB-C video/data priority; not U2723QE.

Read the original source

Source-documented education. Hardware behavior and independent human review have not been performed for these examples.

Draft a correction · More connection lessons