Fan on max speed regardless of cpu temperature

NoniM · 05-21-2018, 11:11 PM

My fan runs at maximum speed regardless of cpu temperature. Here is the output of sensors:

Code:

thinkpad-isa-0000
Adapter: ISA adapter
fan1:        3816 RPM

acpitz-virtual-0
Adapter: Virtual device
temp1:        +47.0°C  (crit = +90.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Core 0:       +39.0°C  (high = +90.0°C, crit = +90.0°C)
Core 1:       +39.0°C  (high = +90.0°C, crit = +90.0°C)
Core 2:       +32.0°C  (high = +90.0°C, crit = +90.0°C)
Core 3:       +32.0°C  (high = +90.0°C, crit = +90.0°C)

Something curious is that acpitz-virtual-0 never changes and always shows 47C. My computer is a Lenovo Yoga 11e running Ubuntu 17.10. Any help would be appreciated. I also asked this question on ask ubuntu.

MensaWater · 05-22-2018, 07:58 AM

BIOS can also control fan speed. You could boot up and interrupt boot going into BIOS settings to investigate.

Some systems in BIOS allow you to change the setting so that it is always high. One might do this if there were components which themselves might overheat even if the system doesn't think the overall temperature is too high. We have some servers with SSD drives in HBA slots that exceed their own heat tolerance even though system board heat is OK. We had to turn on high fan speed so they'd stay cool enough.

NoniM · 05-22-2018, 09:57 AM

I tried opening the BIOS settings and changing the thermal management scheme from "performance" to "balanced". This didn't seem to change the fan behaviour. Is there a way to check if BIOS is controlling fan speed?

I noticed something else interesting, which is that immediately after boot, the fan is off and acpitz-virtual-0 reads a higher temperature of 53C. After the computer goes under sufficient load for the first time, acpitz-virtual-0 drops to 47C and the fan turns on at maximum speed. From then on, acpitz-virtual-0 nor the fan speed ever changes, regardless of CPU temperature.

AwesomeMachine · 05-23-2018, 03:55 PM

It sounds like a glitch in the way Linux is handling acpi.

Stéphane Ascoët · 05-29-2018, 08:03 AM

Or in the ACPI implementation in the computer, or a bug with sensor management