Black screen on boot

• SteamOS version: VERSION_ID=3.8.26, BUILD_ID=20260827.1
• Opted into Steam client beta?: Yes
• Opted into SteamOS beta?: Yes
• Have you checked for updates in Settings > System?: Yes

Issue

On SteamOS, a Samsung Odyssey G7 connected via DisplayPort to an AMD Radeon RX 9070 XT intermittently/consistently produces a black screen during a cold boot into SteamOS Gaming Mode when the display is configured for 240 Hz.
The monitor itself remains powered on and sound is coming through, but SteamOS/Gamescope does not produce a usable image.
The issue is specific to initializing the physical DisplayPort output at 240 Hz during the SteamOS/Gamescope startup sequence.

Working solution

Set the Samsung Odyssey G7 to 60 Hz before booting SteamOS.
With the display starting at 60 Hz:

• SteamOS boots successfully into Gaming Mode.
• The display becomes usable.
• HDR subsequently activates/reconfigures normally.
• The system remains usable without needing to physically reconnect the DisplayPort cable.

steamos_gamescope_g7_240hz_bug_report.md

Start with steamos_gamescope_g7_240hz_bug_report.md and reproduce a cold boot into SteamOS Gaming Mode with the Samsung Odyssey G7 at 240 Hz over DisplayPort. Compare behavior with the monitor set to 60 Hz, and consider the issue complete when the 240 Hz configuration boots to a usable image without requiring cable reconnection.