Hi, I notice a bug report on Bugzilla [1]. Quoting from it:

I have an Asus Pro B550M-C/CSM motherboard, which uses a Realtek ALC887-VD, and a monitor (with speakers) plugged in via DisplayPort. On booting normally, I get no sound from the monitor speakers (other sound outputs like USB or bluetooth headphones work fine).

I have found two workarounds for getting the monitor sound working: 1. rmmod snd_hda_intel && modprobe snd_hda_intel 2. ensure that snd_hda_codec_realtek is inserted before snd_hda_intel (e.g. by adding `softdep snd_hda_intel pre: snd_hda_codec_realtek` in modprobe.d)

Notably, timing does not seem to be an issue: even if snd_hda_intel is blacklisted from loading at boot, it will not work when it is loaded unless is is unloaded and loaded again or snd_hda_codec_realtek is loaded first.

This is not a recent regression - it has been happening as long as I have had the hardware (since at least late 2021).

Since it's not clear which is more useful, I am attaching two runs of alsa-info.sh - one is from a normal boot with sound not working, and the other is after running rmmod snd_hda_intel && modprobe snd_hda_intel with sound working.

See Bugzilla for the full thread and alsa-input output on both working and buggy cases. AFAIK, it looks like module dependency issue. Thanks. [1]: https://bugzilla.kernel.org/show_bug.cgi?id=218027 -- An old man doll... just what I always wanted! - Clara