Fan periodically and suddenly bursts to maximum on duffy (ASUS Chromebox 4 5205U)

[tofurky]

I've noticed kind of annoying fan behavior on duffy; I'm not positive it's due to recent updates as I had this in storage for a year until a few weeks ago, then immediately updated to 2405 and then to 2408 a few days later.

When otherwise idle, the fan quickly and loudly spins up for a second or so, then becomes silent again. It's not a constant cycling, in fact, the bursts of fan activity seem to mostly occur during idle, e.g. after stopping video playback, though it may just be I only notice it then because things are quiet.

ectool console showed many instances of this message:

[111941.653112 Fan 0 stalled!]
[111942.652732 Fan 0 stalled!]
[111981.693959 Fan 0 stalled!]
[111982.696236 Fan 0 stalled!]
[111983.696886 Fan 0 stalled!]
[111984.698517 Fan 0 stalled!]
[112252.928805 Fan 0 stalled!]
[112253.930144 Fan 0 stalled!]
[112254.931623 Fan 0 stalled!]
[112255.933580 Fan 0 stalled!]
[112639.310991 Fan 0 stalled!]
[112640.313072 Fan 0 stalled!]
[112641.313536 Fan 0 stalled!]
[112642.315261 Fan 0 stalled!]
[113452.048656 Fan 0 stalled!]
[113453.048934 Fan 0 stalled!]
[113454.049856 Fan 0 stalled!]
[113455.052018 Fan 0 stalled!]

root@pico:~# ectool --dev=0 --interface=lpc thermalget
sensor  warn  high  halt   fan_off fan_max   name
  0        0   341    351    314     345     Core

I saw this in release notes: Fixed fan control on 10th-gen Chromeboxes. 5205u would be 10th gen according to Intel, so it seems this board may have been in scope for the change.

Manually setting fan speed works as expected; I think it is physically OK.

Thanks, please let me know if you need more information. I could start logging temperatures etc.

Also, some more details:

• Using full UEFI
• Ubuntu 24.04