USB-CEC Adapter — 4K Resolution

The USB-CEC Adapter supports 4K@60Hz 4:2:0 and passes the HDMI video signal through it alongside CEC communication. Pulse-Eight's R&D team has tested the adapter at 4K resolutions and has not been able to replicate signal issues at higher specifications.

If you are experiencing a no signal or blank picture issue while using the adapter at 4K, this is most likely caused by something other than the adapter itself — such as cable quality, EDID, or TV compatibility. Work through the steps below before assuming the adapter is the cause.

Step 1 — Check Your HDMI Cables

4K signals require HDMI cables rated for the bandwidth you are using. Ensure you are using:

• High Speed HDMI cables (18Gbps) for 4K@60Hz 4:2:0
• Ultra High Speed HDMI cables (48Gbps) for 4K@60Hz 4:4:4 or HDR

Try replacing both the cable from your PC to the adapter, and from the adapter to the TV, with known-good cables rated for your resolution.

Step 2 — Check the HDMI Port on Your TV

Not all HDMI ports on a TV support the same bandwidth. Check your TV's manual to confirm that the port you are using supports 4K@60Hz. On most TVs, only specific ports (often labelled HDMI 2.0 or ARC) support full 4K bandwidth.

Step 3 — Check Your Graphics Card Output Settings

Confirm that your PC's graphics card is set to output at the correct resolution and colour format. In Windows, go to Display Settings → Advanced Display → Display Adapter Properties → Colour Management and verify the output matches what your TV supports.

If You Are Still Experiencing Issues — Two-Cable Workaround

If you have worked through the steps above and are still experiencing signal problems specifically when the adapter is in the HDMI path, you can use a two-cable setup to remove the adapter from the signal path entirely while retaining full CEC functionality:

• Cable 1: PC → TV HDMI input 1 — your main picture cable at full 4K quality, no adapter in the path
• Cable 2: PC → USB-CEC Adapter → TV HDMI input 2 — CEC control only, not used for picture

Your TV displays the picture from Cable 1 at full 4K. The CEC adapter on Cable 2 handles all CEC communication even though no picture is displayed on that input.