TL;DR: Streaming from an AMD host to physical Steam Link hardware causes periodic black screen flickers/signal drops, specifically triggered by high-complexity frames (menus, bright particle flashes like consuming a Rune in Elden Ring). Disabling AMF (switching to software x264) or using Sunshine/Moonlight fixes the flicker, proving it's an issue with Steam's specific AMF integration and bitrate spikes.

* Host CPU: AMD Ryzen 7 9800X3D
* Host GPU: AMD Radeon RX 9070XT
* Client: Steam Link hardware, beta channel, build 924
* Display: Philips 5500-series TV (~2018), 60Hz, HDMI

* Periodic black flickers / brief signal dropouts while streaming, occurring primarily:
During menu transitions and menu navigation.

* At moments of sudden high-intensity visual effects (reliable, reproducible trigger: Starting a new game in Elden Ring and scrolling left/right in the
class select menu).

* The host PC's own display output shows no corruption or issue during these events — the problem is isolated to the Steam Link's received/decoded stream.

1. Disabling AMD hardware encoding on the host (forcing software x264) eliminates the flicker entirely. The tradeoff is unacceptable added latency, even on a 9800X3D.

2. Capping FPS via the Steam Link client itself (not in-game) does not eliminate the flickering. Capping FPS in-game does not help either. But during a bug caused by scaling issues, the fps dropped to 30 and in this instance the flickering stopped.

3. Locking bitrate to a lower value (3 Mbps) also eliminates the flicker, but introduces freezing/stutter instead due to insufficient bitrate for complex scenes. Even locking it to 10 Mbps seems to work fine. A value higher than 10 Mbps introduces the flickering and increasing it more only makes the flickering more prevalent. This supports the theory that the issue is tied to the AMF encoder's periodic bitrate re-estimation/restart behavior, which produces large bitrate spikes when a static/low-motion scene is suddenly followed by high-motion or high-contrast content.

4. HEVC is not offered as a decode option on this Steam Link hardware, consistent with the unit's Marvell DE3005-A1 (ARMADA 1500-mini) SoC, which has no HEVC hardware decode block. Testing is therefore limited to the H.264 hardware decode path.

* Swapped HDMI cables (multiple) and HDMI ports on both host and TV.

* Enabled "PC mode" on the TV.

* Disabled HDCP support, FreeSync, Radeon Anti-Lag, and Enhanced Sync in AMD Adrenalin.

* Forced 1080p resolution and capped fps to the TV’s refresh rate.

* Tested "Fast" and "Balanced" streaming quality profiles.

* Disabled Steam Overlay, Windows HAGS (with reboot), and V-Sync.

* Toggled hardware/software decoding on the Steam Link client itself.

As a workaround, Moonlight was sideloaded onto the Steam Link hardware and paired with Sunshine as the host streaming server, replacing Steam's built-in Remote Play entirely.

* This eliminates the AMD AMF flicker issue, supporting the conclusion that the root cause is specific to Steam's own AMF integration rather than the AMD driver, the Steam Link decoder hardware, or the display chain.

* Note on Moonlight setup: It introduces separate, unrelated bugs (ethernet duplex/speed auto-negotiation issues causing network warnings unless switched to 5GHz Wi-Fi, added latency and other network related issues)

The evidence points to a defect in Steam's specific AMF (AMD hardware encoder) integration for Remote Play / Steam Link streaming — likely related to the encoder's periodic bitrate re-estimation causing spikes that the Steam Link's H.264 decode path cannot gracefully handle. This appears to be a long-standing issue that has not been resolved across many driver and firmware versions.

Happy to provide log files⁠, or run further tests if useful for reproducing this on Valve's end.