Even though the hardware supports it, the Valve Steam Machine has been announced with HDMI 2.0 support, rather than the HDMI 2.1 one. Speaking to Ars Technica, Valve clarified the situation, saying that it has been working hard to try and push the HDMI Forum, the consortium responsible for HDMI standard, to allow open-source support for HDMI 2.1 on Linux, and thus the SteamOS.

Back in 2024, AMD already tried a similar thing trying to bring HDMI 2.1 features to its open-source Linux graphics driver but was rejected by the HDMI Forum. Currently, implementation is not possible "without violating HDMI Forum requirements", according to AMD.

Hopefully, Valve might be able to bring at least the HDMI 2.1 support before the Steam Machine launches, especially since the HDMI Forum has released the HDMI 2.2 standard earlier this year.