Knowledge Base for Cable Matters Connectivity Products

Firmware Update for 4K@120hz on macOS - Cable Matters 48Gbps HDMI Video Adapters (201428, 201328)

Article ID: 177
Last updated: 19 Jul, 2024

Cable Matters released a custom firmware update for their USB-C to HDMI 2.1 adapters that allow macOS users to achieve 4K@120hz when connected to an HDMI display via USB-C. 

Applies to

This firmware update applies to the following Cable Matters products:

You may download the macOS firmware and firmware update instructions for these products by following the link here.

Firmware Update Instructions

Each Cable Matters adapter has a specific firmware version. Please check the model number of your adapter before updating the firmware.

If you are unsure which adapter or cable you have, please contact us at and we will be happy to assist.

Note: 1. A Windows laptop that supports DP Alt Mode over the USB-C is required to flash the firmware.

*The monitor must be connected via the Cable Matters adapter and recognized in the Windows display settings when opening the VMMDPTool and throughout the firmware update process.*

          2. There could be some unforeseen compatibility issues after flashing the custom firmware.

Firmware Update Troubleshooting

  1. If an error message appears when first starting the VmmDPTool.exe program, ensure the program is running as an Administrator and check that the video adapter is connected to a display and the host computer’s video port.
  2. The firmware update should be completed with a Windows computer that supports USB-C with DP Alt mode. If you don’t have access to a Windows computer that supports USB-C with DP Alt mode, please try it by using Parallels with Windows running (on Mac).
  3. If the provided VmmDPTool doesn’t work, please try downloading the VmmHIDTool (which is a different tool from the VmmDPTool) from the Windows store, to see if it works.
  4. After performing the update, the adapter may be limited to 1080p with some Windows computers.
  5. To ensure that you have the best experience while using this new firmware with your Mac Device, please be sure to have the latest macOS version installed.
  6. This firmware is compatible with all M1/M2/M3 Macs including MacBook Pro, Mac Mini, MacBook Air, etc. Most Intel-based MacBooks can only output 4K@60hz with this firmware.
  7. The MacBook Pro 2019 will output 4K@120hz with this firmware, but there is some no sound issue.
  8. You can revert to the regular firmware if the custom firmware causes any problems. The regular firmware can be updated by referring to the links below:
Article ID: 177
Last updated: 19 Jul, 2024
Revision: 4

Attached files

Also listed in