With macOS Tahoe (version 26), M3 and M4 Macs now support display modes beyond 4K 60Hz when using supported USB-C to HDMI adapters. Earlier workarounds required a Thunderbolt connection, using USB- to CDP conversion, or even some firmware tricks where USB-C to HDMI converters would “spoof” themselves as DisplayPort sources to achieve higher refresh rates.

Protocol converters such as our USBC-HDMI8K with the Synaptics VMM7100 and supported firmware can now negotiate FRL directly with the OS and the display, with no firmware hacks or tricks needed. macOS 26 takes advantage of a standards-defined feature called Regulated Autonomous (RA) mode, introduced in recent updates to the VESA DisplayPort spec. This shifts more of the link setup into the converter IC while ensuring the adapter operates within standards-compliant modes for stability.

For end users, the requirements are straightforward: an M3 or M4 Mac running macOS 26 Tahoe, an HDMI 2.1-capable display (and video cable), and a USB-C to HDMI adapter with an FRL-capable IC and firmware. In our testing, adapters like our USBC-HDMI8K (based on the Synaptics VMM7100) are now running 4K 120Hz under macOS 26 (additional validation and testing is required on base M1 and M2 systems, but they did not support the feature in our beta OS testing). We’ll have a firmware update available soon and will update this post with a link when available, along with any relevant updated testing results.

We’re excited for this change and wanted to share this news with the community! Let us know in a comment if you have tested this or plan to test this feature.