HP Elite Mini 600 G9 fan curve too conservative under CPU load?

I’m trying to diagnose fan behavior on an HP Elite Mini 600 G9 running Proxmox.

Specs:

- HP Elite Mini 600 G9

- BIOS U21 02.22.01, 05/14/2026

- i7-13700T

- Proxmox kernel 7.0.12-1-pve

Issue: under sustained CPU load, the CPU sits around 82–85°C, but the fan does not ramp very aggressively. With hp-wmi-sensors loaded, I can read fan RPM. Linux does not seem able to control it.

What I tested:

- BIOS Increase Idle Fan Speed(%) = 30: fan sits around 3440 RPM, but does not really ramp further under load.

- BIOS Increase Idle Fan Speed(%) = 0: fan starts lower, around 2300–2700 RPM, then ramps under stress, but only to about 3390–3630 RPM.

- CPU package power stays around 35W.

- No CPU thermal throttling counters.

- Manual writes to HP WMI fan control fail with Invalid argument.

- Kernel logs show HP WMI errors like Failed to apply initial fan settings: -22.

So it looks like HP firmware/EC is choosing a quiet fan curve and allowing low-80s CPU temps, rather than Proxmox controlling the fan.

is there any hidden BIOS setting, HP tool, firmware option, or known workaround to make the Elite Mini 600 G9 use a more aggressive automatic fan curve without setting Increase Idle Fan Speed to 100% all the time?