Fan speed control (简体中文)

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翻译状态: 本文是英文页面 Fan speed control翻译,最后翻译时间:2017-08-31,点击这里可以查看翻译后英文页面的改动。

Fancontrol, 是lm_sensors的一部分,可以被用于控制CPU以及其他风扇的转速。本文阐述了如何安装,配置它。



许多较新主板的传感器仍然未受到Kernel内建驱动的支持,检查一下表格 lm-sensors devices 来确认驱动支持情况。

我们不建议使用lm_sensors.service 来加载驱动模块,请手动将配置文件放入/etc/modules-load.d/load_these.conf,使用 lm_sensors.service 可能导致设备地址在每次启动时变化。 在 /etc/conf.d/lm_sensors 你可以找到模块, 如果没有,请以root运行sensors-detect使用默认设置。 在modules-load.d一行行地加入。参见[1]


设置 lm_sensors

$ sensors
Adapter: ISA adapter
Core 0:      +29.0°C  (high = +76.0°C, crit = +100.0°C)  


Adapter: ISA adapter
Vcc:         +1.14 V  (min =  +0.00 V, max =  +4.08 V)   
VTT:         +2.08 V  (min =  +0.00 V, max =  +4.08 V)   
+3.3V:       +3.33 V  (min =  +0.00 V, max =  +4.08 V)   
NB Vcore:    +0.03 V  (min =  +0.00 V, max =  +4.08 V)   
VDRAM:       +2.13 V  (min =  +0.00 V, max =  +4.08 V)   
fan1:        690 RPM  (min =   10 RPM)
temp1:       +37.5°C  (low  = +129.5°C, high = +129.5°C)  sensor = thermistor
temp2:       +25.0°C  (low  = +127.0°C, high = +127.0°C)  sensor = thermal diode


增加 fan_div



chip "coretemp-isa-*"
set fanX_div 4



# sensors -s


再次运行 sensors ,看一下有没有读出RPM的值。如果没有,把_div后面的数增加到8, 16, 或32。重复尝试!


Note: Advanced users may want to skip this section and write /etc/fancontrol on their own, which also saves them from hearing all of the fans at full speed.

Once sensors is properly configured, run pwmconfig to test and configure speed control. Follow the instructions in pwmconfig to set up basic speeds. The default configuration options should create a new file, /etc/fancontrol.


Warning: Some of the steps outlined below describe how to tweak fan speeds. Before doing this be sure to have a low CPU load.
Note: On several systems, the included script may report errors as it tries to calibrate fans to the respective pulse-width modulation (PWM). Users may safely ignore these errors. The problem is that the script does not wait long enough before ramping up or down the PWM.

Users wishing more more control may need to tweak the generated configuration. Here is a sample configuration file:

DEVPATH=hwmon0=devices/platform/coretemp.0 hwmon2=devices/platform/w83627ehf.656
DEVNAME=hwmon0=coretemp hwmon2=w83627dhg
FCFANS= hwmon0/device/pwm1=hwmon0/device/fan1_input
  • INTERVAL: how often the daemon should poll CPU temps and adjust fan speeds. INTERVAL is in seconds.

The rest of the configuration file is split into (at least) two values per configuration option. Each configuration option first points to a PWM device which is written to which sets the fan speed. The second "field" is the actual value to set. This allows monitoring and controlling multiple fans and temperatures.

  • FCTEMPS: The temperature input device to read for CPU temperature. The above example corresponds to /sys/class/hwmon/hwmon0/device/temp1_input.
  • FCFANS: The current fan speed, which can be read (like the temperature) in /sys/class/hwmon/hwmon0/device/fan1_input
  • MINTEMP: The temperature (°C) at which to SHUT OFF the CPU fan. Efficient CPUs often will not need a fan while idling. Be sure to set this to a temperature that you know is safe. Setting this to 0 is not recommended and may ruin your hardware!
  • MAXTEMP: The temperature (°C) at which to spin the fan at its MAXIMUM speed. This should be probably be set to perhaps 10 or 20 degrees (°C) below your CPU's critical/shutdown temperature. Setting it closer to MINTEMP will result in higher fan speeds overall.
  • MINSTOP: The PWM value at which your fan stops spinning. Each fan is a little different. Power tweakers can echo different values (between 0 and 255) to /sys/class/hwmon/hwmon0/device/pwm1 and then watch the CPU fan. When the CPU fan stops, use this value.
  • MINSTART: The PWM value at which your fan starts to spin again. This is often a higher value than MINSTOP as more voltage is required to overcome inertia.

There are also two settings fancontrol needs to verify the configuration file is still up to date. The lines start with the setting name and a equality sign, followed by groups of hwmon-class-device=setting, seperated by spaces. You need to specify each setting for each hwmon class device you use anywhere in the config, or fancontrol will not work.

  • DEVPATH: Sets the physical device. You can determine this by executing the command
readlink -f /sys/class/hwmon/hwmon-device/device | sed -e 's/^\/sys\///'
  • DEVNAME: Sets the name of the device. Try:
$ sed -e 's/[[:space:]=]/_/g' /sys/class/hwmon/hwmon-device/device/name
Tip: Use MAXPWM and MINPWM options that limit fan speed range. See fancontrol manual page for details.
Tip: Not only the DEVPATH may change on reboot due to different timing of module loading, but also e.g. the temperature sensor paths (hwmon0/device/temp1_input becomes hwmon0/temp1_input). This usually happens on a kernel update. Check the system log to find out which is the troublemaker:
# systemctl status fancontrol.service
and correct your config file accordingly.


Try to run fancontrol:

# /usr/bin/fancontrol

A properly configured setup will not error out and will take control of system fans. Users should hear system fans slowing shortly after executing this command.

To make fancontrol start automatically on every boot, enable fancontrol.service.

Note: Upon upgrading/changing the kernel, running fancontrol may result in an error regarding changed device paths. This issue may be fixed by running sensors-detect and restarting the system.


i8kutilsAUR provides an alternative method of controlling the fan speed on some Dell Inspiron and Latitude laptops. It makes use of the /proc/i8k interface provided by the dell_smm_hwmon driver (formerly i8k). Results will vary depending on the exact model of laptop.


tcl must be installed in order to run i8kmon as a background service (using the --daemon option). To run the X11 desktop applet, tk is required as well.


By default, i8kmon only monitors the CPU temperature and fan speed passively. To enable its fan speed control, either run it with the --auto option or enable the option permanently in /etc/i8kutils/i8kmon.conf:

set config(auto)       1

The temperature points at which the fan changes speed can be adjusted in the same configuration file. Only three fans speeds are supported (high, low, and off). Look for a section similar to the following:

set config(0)  {{0 0}  -1  55  -1  55}
set config(1)  {{1 1}  45  75  45  75}
set config(2)  {{2 2}  65 128  65 128}

This example starts the fan at low speed when the CPU temperature reaches 55 °C, switching to high speed at 75 °C. The fan will switch back to low speed once the temperature drops to 65 °C, and turns off completely at 45 °C.

Disable BIOS fan speed control

It may be necessary to turn off control of the fan speed by the BIOS to prevent it from "fighting" with i8kmon. On some laptops, this can be done using the smm utility. This utility is extremely dangerous as it writes directly to an I/O port to invoke the processor's System Management Mode. Use it at your own risk.

smm must be compiled and installed manually. On a 64-bit system, gcc-multilib[broken link: replaced by gcc] is required. Locate the file smm.c in the i8kutils source and compile it:

$ gcc -m32 -o smm smm.c

To disable BIOS fan speed control, run (as root):

# ./smm 30a3

To enable it again:

# ./smm 31a3
Note: This method may disable other power management features of the BIOS as well, such as notifying Linux when the power button is pressed.

Installation as a service

i8kmon can be started automatically as a systemd service using a unit file similar to the following:


#ExecStartPre=/usr/bin/smm 30a3  # uncomment to disable BIOS fan control
#ExecStopPost=/usr/bin/smm 31a3  # ... and re-enable it afterwards
ExecStart=/usr/bin/i8kmon -d