The HDMI Forum, responsible for the HDMI specification, continues to stonewall open source. Valve's Steam Machine theoretically supports HDMI 2.1, but the mini-PC is software-limited to HDMI 2.0. As a result, more than 60 frames per second at 4K resolution are only possible with limitations.
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In a statement to Ars Technica, a Valve spokesperson confirmed that HDMI 2.1 support is "still a work-in-progress on the software side." "We’ve been working on trying to unblock things there."
The Steam Machine uses an AMD Ryzen APU with a Radeon graphics unit. Valve strictly adheres to open-source drivers, but the HDMI Forum is unwilling to disclose the 2.1 specification. According to Valve, they have validated the HDMI 2.1 hardware under Windows to ensure basic functionality.
No Change After Almost Two Years
The restriction imposed by the HDMI Forum was already criticized in early 2024 by an AMD employee responsible for Linux. Even then, according to AMD, they had submitted a functional, HDMI 2.1-compatible driver, which the HDMI Forum rejected.
"Unfortunately, the HDMI Forum rejected our proposal," it was stated at the time. "At this time an open source HDMI 2.1 implementation is not possible without running afoul of the HDMI Forum requirements."
Only HDMI 2.1 offers sufficient bandwidth for 120 or 144 Hertz at 3840 × 2160 pixels without compression. Furthermore, this version introduced manufacturer-independent variable refresh rates (HDMI VRR). Valve enables 4K and 120 Hertz using chroma subsampling, a compression technique that is particularly noticeable with text. VRR functions in the form of AMD's Freesync, which requires compatible displays.
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Alternatively, interested parties can use an active adapter from DisplayPort 1.4 to HDMI 2.1 to increase the frame rate without compression. However, they do not officially support VRR. Popular variants from Club3D are no longer available; offers from less well-known providers (starting from 35,67 €) are still available in price comparisons.
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