DSC with 4 monitors: 3440x1440@240Hz on DP-1 causes other outputs to drop (works on Windows)

NVIDIA Open GPU Kernel Modules Version

610.57.04

Please confirm this issue does not happen with the proprietary driver (of the same version). This issue tracker is only for bugs specific to the open kernel driver.

• I confirm that this does not happen with the proprietary driver package.

Operating System and Version

CachyOS Linux (Arch-based), rolling release - CachyOS — BUILD_ID=rolling

Kernel Release

7.1.6-1-cachyos (pacote linux-cachyos-nvidia-open — com o módulo NVIDIA embutido)

Please confirm you are running a stable release kernel (e.g. not a -rc). We do not accept bug reports for unreleased kernels.

• I am running on a stable kernel release.

Hardware: GPU

5090

Describe the bug

RTX 5090, nvidia-open 610.57.04, Wayland (COSMIC). 4 monitors on 4 separate ports. Setting DP-1 (3440x1440) to 240 Hz — which requires DSC over DP 1.4 bandwidth — causes one or more other monitors to fail. Setting DP-1 to 60 Hz (no DSC) makes all 4 work. Same GPU/monitors/cables on Windows 11 drives all 4 at 240 Hz without issue, so DSC budget allocation across outputs is broken in the Linux driver.

OS: CachyOS Linux (rolling)
Kernel: 7.1.6-1-cachyos
GPU: NVIDIA RTX 5090 — nvidia-open 610.57.04
Compositor: cosmic-comp 1.5.0 (Wayland)

To Reproduce

4 monitor displays 1 with higher hertz like 260hz

Bug Incidence

Once

nvidia-bug-report.log.gz

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More Info

No response

No source file or test is identified. Start by reproducing the four-monitor setup on CachyOS with an RTX 5090, using DP-1 at 3440x1440@240Hz and then 60Hz, while checking the NVIDIA bug report and the proprietary-driver comparison. Done means all four outputs remain active at the high refresh rate.