Machine: Dell Latitude x5530 vPro 01 Distro: regardless, but currently Debian buster (testing) I find behavior of machine with loaded dell_smm_hwmon strange. once fan turns on due to heat, it stops very late. according to sensors dell_smm-virtual-0 Adapter: Virtual device Processor Fan: 3202 RPM CPU: +39.0°C Ambient: +42.0°C SODIMM: +41.0°C while after circa 5mins of constant fan noise dell_smm-virtual-0 Adapter: Virtual device Processor Fan: 0 RPM CPU: +40.0°C Ambient: +42.0°C SODIMM: +40.0°C Temperature can drop as low as 35 degs and fan will happily break nights' calm. Moreover, dedicated program i8[mon|fan|ctl] ignores my forcing of turning cooler down root@phoebe:~# i8kctl fan 0 0 -1 1 It looks for me like hardware is still controlled on lower lever (bios?). These manufacturer's rules are unacceptable for me; OpenIndiana does not have any helpers to interact with fan so while using this OS i am forced to suffer because of this near random behaviour. I didn't checked cooler behaviour under Windows, as i replaced OS right after reaching home with new laptop :)
I have the same problem (on a Dell Precision 5530, with Debian unstable). It appears that the problem is related to the BIOS not actually giving up on directly controlling the fan speed. An undocumented call to disable the BIOS control of the fans was discovered and is available here: https://github.com/clopez/dellfan It would probably be nice to integrate this call in the dell-smm-hwmon module.