Fan control scripts

This page provides several scripts for controlling the ThinkPad's system fan according the its thermal sensors (overriding the embedded controller), in order to reduce fan noise and decrease power consumption. ATTENTION! These scripts rely on undocumented hardware features and override nominal hardware behavior. They may thus cause arbitrary damage to your laptop or data. Watch your temperatures!

Variable speed control scripts

The following scripts sets the fan speed according to the system's thermal sensors. In addition, they include a hack for preventing the annoying fan pulsing that occurs on some systems. Note that the fan levels, thresholds and anti-pulsing hacks are system-specific, so you may need to adjust them.

Comprehensive bash script with fine control over fan speed

The following requires only ibm-acpi 0.11 or higher (e.g., as found in kernel 2.6.14 and higher) with the experimental=1 module parameter. It supports (optional) daemon mode and logging to syslog.

This scripts uses a different temperature range for each thermal sensor, since they have different specs and thermal systems. For each sensor, a fan level is chosen based on the minimum and maximum temperatures configured for that sensor; then the actual fan level is set to the slowest that will satisfy all sensors. There are also some hysteresis features - see the script for the details. The method of controlling fan speed is documented here.

Current options:

Usage: ./tp-fancontrol [OPTION]...

Available options:
  -s N   shift up temperature thresholds by N degrees
         (positive for quieter, negative for cooler)
  -t     test mode
  -q     quiet mode
  -d     daemon mode, go into background (implies -q)
  -l     log to syslog
  -k     kill already-running daemon
  -u     tell already-running daemon that the system is being suspended
  -p     pid file location for daemon mode, default: $PID_FILE

ATTENTION!

The list of temperature ranges used below is much more liberal than the rules used by the embedded controller firmware, and is derived mostly from anecdotal evidence, hunches and wishful thinking. It is also model-specific - see thermal sensors.

The script: tp-fancontrol (download)

init script for the comprehensive script

The following init script (tested on Debian) allows you to configure some options using a config file. It requires to move the above tp-fancontrol script to /usr/bin/tp-fancontrol, but that can be changed easily.

• Init script: tp-fancontrol.init (download) (save as /etc/init.d/tp-fancontrol
• Configuration file: tp-fancontrol.conf (download) (save as /etc/tp-fancontrol.conf)

Simple bash script with fine control over fan speed (requires kernel patch)

The following is a simpler patch (without extra features like daemon mode and logging). It requires the patch for controlling fan speed.

#!/bin/bash

# This script dynamically controls fan speed on some ThinkPad models
# according to user-defined temperature thresholds.  It implements its
# own decision algorithm, overriding the ThinkPad embedded
# controller. It also implements a workaround for the fan noise pulse
# experienced every few seconds on some ThinkPads.
#
# The script requires the ibm_acpi patch at 
# http://thinkwiki.org/wiki/Patch_for_controlling_fan_speed
#
# WARNING: This script relies on undocumented hardware features and
# overrides nominal hardware behavior. It may thus cause arbitrary
# damage to your laptop or data. Watch your temperatures!
#
# This file is placed in the public domain and may be freely distributed.

LEVELS=(    0      2      4      7)  # Fan speed levels
UP_TEMPS=(      52     60     68  )  # Speed increase trip points
DOWN_TEMPS=(  48     56     64    )  # Speed decrease trip points

ANTIPULSE=( 0      1      0      0)  # Prevent fan pulsing noise at this level
                                     #   (this also prevents fan speed updates)

IBM_ACPI=/proc/acpi/ibm
FAN=$IBM_ACPI/fan
INTERVAL=3
VERBOSE=true
DRY_RUN=false

[[ "$1" == "-t" ]] && { DRY_RUN=true; echo "$0: Dry run, will not change fan state."; }

# Enable the fan in default mode if anything goes wrong:
set -e -E -u
$DRY_RUN || trap "echo enable > $FAN; exit 0" EXIT HUP INT ABRT QUIT SEGV TERM


thermometer() { # output list of temperatures
    read X Y < $IBM_ACPI/thermal
    [[ "$X" == "temperatures:" ]] || { 
	echo "$0: Bad temperatures: $X $Y" >&2 
	exit 1
    }
    echo "$Y"; 
}

speedometer() { # output fan speed
    cat $FAN | sed '/^speed/!d; s/speed:[ \t]*//'
}

IDX=0
MAX_IDX=$(( ${#LEVELS[@]} - 1 ))
SETTLE=0

while true; do
    TEMPS=`thermometer`
    $VERBOSE && SPEED=`speedometer`

    # Calculate new level
    NEWIDX=$IDX
    DOWN=$(( IDX > 0 ))
    for TEMP in $TEMPS; do
        # Increase speed as much as needed
        while [[ $NEWIDX -lt $MAX_IDX ]] && 
              [[ $TEMP -ge ${UP_TEMPS[$NEWIDX]} ]]; do
            (( NEWIDX ++ ))
            DOWN=0
        done
        # Allow decrease (by one index)?
        if [[ $DOWN == 1 ]] && 
           [[ $TEMP -gt ${DOWN_TEMPS[$(( IDX - 1 ))]} ]]; then
            DOWN=0
        fi
    done
    if [[ $DOWN == 1 ]]; then
        NEWIDX=$(( IDX - 1 ))
    fi

    # Transition
    OLDLEVEL=${LEVELS[$IDX]}
    NEWLEVEL=${LEVELS[$NEWIDX]}
    $VERBOSE && echo "tpfan: Temps: $TEMPS   Fan: $SPEED   Level: $OLDLEVEL->$NEWLEVEL"
    $DRY_RUN || echo level $NEWLEVEL > $FAN

    sleep $INTERVAL

    # If needed, apply anti-pulsing hack after a settle-down period:
    if [[ ${ANTIPULSE[${NEWIDX}]} == 1 ]]; then
	if [[ $NEWLEVEL == $OLDLEVEL ]]; then
	    if [[ $SETTLE -ge 0 ]]; then
		(( SETTLE -= INTERVAL ))
	    else
		$DRY_RUN || echo level disengaged >> $FAN
		sleep 0.5
	    fi
	else
	    SETTLE=6
	fi
    fi

    IDX=$NEWIDX
done

The author of the script disclaims all warranty for this script, and releases it to the public domain (meaning you may use it and further distribute it under any terms you wish, including incorporating it into other software).

Fan enable/disable scripts

The following scripts were written before it was known how to control the fan speed, so they only toggle between fan disabled and default (noisy) fan behavior. In some models, they also do not monitor all available thermal sensors.

sh script example

#!/bin/sh

MAXTEMP=50

while [ 1 ];
do
       fan=no

       for temp in `sed s/temperatures:// < /proc/acpi/ibm/thermal`
       do
               test $temp -gt $MAXTEMP && fan=yes
       done

       command='disable'
       test "$fan" = "yes" && command='enable'
       echo $command > /proc/acpi/ibm/fan

       sleep 20
done

sh script with more features

#!/bin/sh

# fan control-script
#
# based upon ibm-acpi 0.11 (experimental=1 !)
#
# eliminates anoying "fan always on" in battery mode
# works with hysteresis (DELTA) so that always-turn-on/turn-off is avoided
# fan acivates at MAXTEMP and cools down CPU, GPU etc. to MAXTEMP-DELTA than the fan is turned off
# furthermore detects if AC is on and gives back fan control to default behaviour than
#
# one can change MAXTEMP and DELTA to individual values
# but take care of your THINKPAD don`t melt it!
#
# have fun!
# mk 05.05.05

MAXTEMP=51
DELTA=4

SWITCHTEMP=$MAXTEMP

#make sure the script doesn't leave the fan off on error
trap "echo enable > /proc/acpi/ibm/fan" EXIT

while [ 1 ];
do
  for ac in `sed s/state:// < /proc/acpi/ac_adapter/AC/state`
    do
     if [ "$ac" = "off-line" ]; then
         fan=no
         for temp in `sed s/temperatures:// < /proc/acpi/ibm/thermal`
           do
             test $temp -gt $SWITCHTEMP && fan=yes
           done

         if [ "$fan" = "yes" ]; then
           command='enable'
           SWITCHTEMP=`expr $MAXTEMP - $DELTA`
         else
           SWITCHTEMP=$MAXTEMP
           command='disable'
         fi

       else # ac-adapter on -> set fan control to standard behaviour
         command='enable'
       fi

       echo $command > /proc/acpi/ibm/fan
       sleep 15
     done 
  done

sh script with extra safety functionality

ibm_acpi usually works well. But to rely on it completely, this script provides some extra safety functionality:

1. It catches various signals and turns the fan on before it quits.
2. It turns off the fan under very strict conditions, leaving it on when unexpected errors occur.

#!/bin/sh

# july 2005 Erik Groeneveld, erik@cq2.nl
# It makes sure the fan is on in case of errors
# and only turns it off when all temps are ok.

IBM_ACPI=/proc/acpi/ibm
THERMOMETER=$IBM_ACPI/thermal
FAN=$IBM_ACPI/fan
MAXTRIPPOINT=65
MINTRIPPOINT=60
TRIPPOINT=$MINTRIPPOINT

echo fancontrol: Thermometer: $THERMOMETER, Fan: $FAN
echo fancontrol: Current `cat $THERMOMETER`
echo fancontrol: Controlling temperatures between $MINTRIPPOINT and $MAXTRIPPOINT degrees.

# Make sure the fan is turned on when the script crashes or is killed
trap "echo enable > $FAN; exit 0" HUP KILL INT ABRT STOP QUIT SEGV TERM

while [ 1 ];
do
       command=enable
       temperatures=`sed s/temperatures:// < $THERMOMETER`
       result=
       for temp in $temperatures
       do
               test $temp -le $TRIPPOINT && result=$result.Ok
       done
       if [ "$result" = ".Ok.Ok.Ok.Ok.Ok.Ok.Ok.Ok" ]; then
               command=disable
               TRIPPOINT=$MAXTRIPPOINT
       else
               command=enable
               TRIPPOINT=$MINTRIPPOINT
       fi
       echo $command > $FAN
       # Temperature ramps up quickly, so pick this not too large:
       sleep 5
done

Init scripts

Init script example

#! /bin/sh

N=/etc/init.d/fan

set -e

case "$1" in
 start)
       # make sure privileges don't persist across reboots
       if [ -d /var/run/fan ] && [ "x`ls /var/run/fan`" != x ]
       then
               touch -t 198501010000 /var/run/fan/*
       fi
       fan.sh &    # Script from above
       ;;
 stop|reload|restart|force-reload)
       killall fan.sh
       echo enable > /proc/acpi/ibm/fan
       ;;
 *)
       echo "Usage: $N {start|stop|restart|force-reload}" >&2
       exit 1
       ;;
esac

exit 0

Init script example for gentoo

Assume one of the above control scripts is /usr/sbin/ibm-fancontrold, for gentoo use the following init script in /etc/init.d/ibm-fancontrol. Copy the script to /etc/init.d/ibm-fancontrol, then do

# rc-update add ibm-fancontrol default

This will add the init script to the default runlevel.

#!/sbin/runscript
# 2005 Gilbert Tiefengruber
# Distributed under the terms of the GNU General Public License v2 
# IBM Fancontrol init script for IBM Thinkpad laptops (tested with R50)
# This init script was written for gentoo 2005.1, kernel 2.6.12
# You need the ibm_acpi kernel module version 0.11 or greater
# load the module with experimental=1 to enable the fan controls

depend() {
        need localmount
}
checkconfig() {
        if [ ! -e /proc/acpi/ibm/fan ]; then
                eerror "The ibm_acpi module must be loaded with (experimental=1)"
                return 1
        fi
} 
start() {
        checkconfig || return 1
        ebegin "Starting ibm-fancontrold"
        start-stop-daemon --quiet -p /var/run/ibm-fancontrold.pid -m -b --start -a /usr/sbin/ibm-fancontrold
        eend ${?}
} 
stop() {
        ebegin "Stopping ibm-fancontrold"
        start-stop-daemon --stop --quiet -p /var/run/ibm-fancontrold.pid
        eend ${?}
}

Other

fanctrld

fanctrld is a daemon (written in C) that controls the Thinkpad's fan. The basic approach is to monitor both temperature and fan speed. The fan is enabled when a certain temperature is exceeded, and disabled when the BIOS slows down the fan below a certain speed.

Ideas for improvement

• Use the HDAPS sensor to automatically lower the temperature thresholds when the laptop is moving. Prolonged movement usually happens when the laptop is on the user's lap (so better keep temperatures down), or when in a moving vehicle where fan noise is typically overshadowed by vehicle noise.
• Use a PID controller feedback loop instead of simple thresholds.

See also

• How to control fan speed
• Shimodax's ThinkPad fan control tool for a Windows offers functionality similar to these scripts; see the forum discussion at thinkpads.com.
• Yury Polyanskiy has a kernel patch for automatic fan control in kernelspace (only enable/disable based on maximum temperature).