Dec 11, 2025 16:00:00

The Steam Machine theoretically supports HDMI 2.1, but the HDMI Forum, which develops the HDMI specification, has refused to open-source it, making it unfeasible to implement.

The Steam Machine , a gaming PC developed by Valve, supports the older HDMI 2.0 standard from 2013, rather than the HDMI 2.1 standard announced in 2017. It has been pointed out that this is because the HDMI Forum, which manages the HDMI standard, has rejected the open source implementation of HDMI 2.1, and the open source AMD driver included with the Steam Machine is not compatible.

Why won't Steam Machine support HDMI 2.1? Digging in on the display standard drama. - Ars Technica
https://arstechnica.com/gaming/2025/12/why-wont-steam-machine-support-hdmi-2-1-digging-in-on-the-display-standard-drama/

Valve: HDMI Forum Continues to Block HDMI 2.1 for Linux | heise online

https://www.heise.de/en/news/Valve-HDMI-Forum-Continues-to-Block-HDMI-2-1-for-Linux-11107440.html

While the Steam Machine hardware itself supports HDMI 2.1, software limitations limit its support to HDMI 2.0. While the original output limit was supposed to be 4K at 60Hz, as per HDMI 2.0, Valve has increased it to 4K at 120Hz using a technique called chroma subsampling.

Valve acknowledged that HDMI 2.1 support is 'still in development on the software side' and said it is 'working to remove any roadblocks.'

Technology media Ars Technica points out that the obstacle is the HDMI Forum's refusal to open-source the HDMI.

The community has been calling for HDMI 2.1 to be made open source for many years, and AMD engineers and others have been cooperating, but the request was

rejected by the HDMI Forum in 2024.

The Steam Machine uses an AMD Ryzen APU and Radeon graphics unit and strictly adheres to open-source drivers, but is unable to support HDMI 2.1 due to a refusal to disclose the specifications. While the HDMI 2.1 specifications are only available to those who subscribe to the HDMI Forum, some of the specifications have been leaked .

The chroma subsampling used by the Steam Machine is said to have 'no significant impact on image quality,' but it has been pointed out that it can result in a decrease in quality due to the reduction in color information, and that text on the screen may become slightly blurred in some text-heavy games.

Additionally, because it doesn't fully support HDMI 2.1, the Steam Machine has limitations when it comes to handling adaptive sync refresh rates (ADR). Additionally, while the Steam Machine supports AMD's FreeSync standard via HDMI, it doesn't support the generic HDMI-VRR standard allowed by the HDMI 2.1 standard. Many HDMI-VRR-compatible monitors don't accurately handle AMD's FreeSync, which can cause issues with some monitors.