Despite recently updating the Steam Machine's product page to more accurately reflect the SteamOS-powered gaming PC's actual 4K performance, Valve has been working behind the scenes for a long time to enable HDMI 2.1 support on Linux in order to have full-featured, high-framerate 4K support over HDMI. In a recent statement to Digital Foundry, Valve engineer Pierre-Loup Griffais has confirmed that its work with AMD to implement HDMI 2.1 with FRL support has been completed, and although full support for HDMI 2.1 has not yet been implemented for the Steam Deck, it will be added in a future update, which will also add support for 4K 240 Hz with DSC over HDMI. The current driver setup already has support for important features, like variable refresh rate over HDMI.

We've worked a ton with various partners in AMD, who has done a ton of work to try and drive resolution there, and we think that's fully resolved. The current software stack we have on Steam Machine has HDMI 2.1 VRR enabled, not only on FreeSync displays but also on HDMI Forum VRR ones. This is a very important part of the performance puzzle, along with the FSR 4 boosts to come.