Asus H770-PLUS D4 and Linux fan control

Partly a note-to-self, partly a note to anyone else who has the same problem.

Out-of-the-box, Linux (at least 5.15.0-69-generic #76-Ubuntu) does not recognise the fans controlled by the Asus H770-PLUS D4 motherboard.

You can confirm this if running sensors shows no fan RPM information, and if the system gets under any kind of load (e.g., running an Android emulator) the fans spin up to what sounds like maximum speed, and stay there, irrespective of the actual CPU temperatures.

To fix this boot the kernel with the acpi_enforce_resources=lax flag.

On my system (Linux Mint) that was by:

  1. Edit /etc/default/grub, adding the flag to the existing GRUB_CMDLINE_LINUX_DEFAULT entry
  2. Run sudo update-grub
  3. Reboot.

Re-run sensors and confirm that there is fan information.