How to control fan speed

2006-12-25T09:52:43Z

Thor: /* Supported models */

This page discusses methods for controlling the system fan.

==For Linux==
===Using a patched kernel===
{{WARN|This patch is superceded by the patches in [[ibm-acpi]] [[Git]] repository}}

The [[Patch for controlling fan speed]] provides a convenient interface via {{path|/proc/acpi/ibm/fan}}.

Manual speed control can be done through the [[patch for controlling fan speed]]:

'''#cat /proc/acpi/ibm/fan'''
status: enabled
level: auto
speed: 4219
commands: enable, disable, level <level>
(<level> is 0-7, auto or disengaged)

'''#echo level 2 > /proc/acpi/ibm/fan'''

'''#cat /proc/acpi/ibm/fan'''
status: enabled
level: 2
speed: 3142
commands: enable, disable, level <level>
(<level> is 0-7, auto or disengaged)

===Using a stock kernel===

If you have the [[ibm-acpi]] module loaded with <tt>experimental=1</tt>, you can control the fan without patching the kernel by directly writing to the relevant embedded controller register using {{path|/proc/acpi/ibm/ecdump}}.

For example:

{{cmdroot|echo 0x2F 0x00 > /proc/acpi/ibm/ecdump}} (fan off)

{{cmdroot|echo 0x2F 0x02 > /proc/acpi/ibm/ecdump}} (low speed)

{{cmdroot|echo 0x2F 0x04 > /proc/acpi/ibm/ecdump}} (medium speed)

{{cmdroot|echo 0x2F 0x07 > /proc/acpi/ibm/ecdump}} (maximum speed)

{{cmdroot|echo 0x2F 0x80 > /proc/acpi/ibm/ecdump}} (automatic - default)

{{cmdroot|echo 0x2F 0x40 > /proc/acpi/ibm/ecdump}} (disengaged)

See the specifications below for the meaning of these modes.

===On/off control using stock kernel===

If you only wish to turn the fan on and off (with automatic control when it's on), you can use the following.

When loading [[ibm-acpi]] v0.11 with experimental switch ({{cmdroot|1=modprobe ibm_acpi experimental=1}}), it is possible to read and write the status of fan:

'''#cat /proc/acpi/ibm/fan'''
status: enabled
speed: 3580
commands: enable, disable

'''#echo disable > /proc/acpi/ibm/fan'''

'''cat /proc/acpi/ibm/fan'''
status: disabled
speed: 0
commands: enable, disable

When off, the fan will then '''never''' wake up. It is advised to use an automated control script to reduce the chance of hardware damage.

===Automated control scripts===

An [[ACPI fan control script#Variable speed control scripts|ACPI fan control script]] can be to override the firmware's fan algorithm with gentler, quieter version. It monitors the laptop's [[thermal sensors]] and sets the fan speed accordingly, according to customizable thresholds. For the default behavior, simply save the [[ACPI fan control script#Variable speed control scripts|script]] as {{path|tp-fancontrol}} and run; note that this script requires you to modprobe the ibm_acpi module as "modprobe ibm_acpi experimental=1"<br />
{{cmdroot|./tp-fancontrol}}

==For Windows==

Shimodax's ThinkPad fan control tool offers similar functionality (see [http://forum.thinkpads.com/viewtopic.php?t=17715 forum discussion] at thinkpads.com). Source and binaries are available through the [http://sourceforge.net/projects/tp4xfancontrol "Tp4xFanControl"] project on SourceForge.

==Hardware specs==

The following hardware behavior was discovered experimentally by [[User:Thinker|Thinker]] and neither provided by nor confirmed by IBM/Lenovo. The following description may be inaccurate and may vary by model (see list of models above). The terminology probably does not match the one used by IBM/Lenovo engineers.

{{NOTE|Information on other models is included in the [[ibm-acpi]] [[Git]] version.}}

ACPI DSDT register _SB.PCI0.LPC.EC.HFSP (8 bits, offset 0x2F in the <tt>EmbeddedController</tt> address space, accessed through the standard EC interface at IO ports 0x62 and 0x66) is read/writable and has the following meaning:

Bits 7 6 5 4 3 2 1 0
---------------
Value 1 0 * * * * * * - automatic
* 1 * * * * * * - disengaged
0 0 N N N N N N - manual (0..63; 0=disable fan, 1=min, ..., 7=max)

In ''automatic'' mode, the embedded controller sets the fan speed automatically according to system temperatures and some unknown algorithm.

In ''manual'' mode, the fan level is forced to the given value and the EC will auto-regulate the fan to maintain at a (roughly) constant RPM, which is model-dependent. Manual speed levels 8-63 yield the same behavior as level 7, and the the ACPI DSDT uses level 7 for the emergency mode it enters upon critical CPU/GPU temperature, so apparently 7 is the real maximum level.

In ''disengaged'' mode, the embedded controller does not read the fan RPM (hence <tt>EmbeddedController</tt> offset 0x84 is not updated), and does not maintain a stable fan speed. When disengaged mode is entered the fan speed is not immediately changed (except if the fan was disabed, in which case it is turned on at a low level). However, once in disengaged mode, fan speed will slowly increase to ''beyond'' the maximum manual level (this may cause hardware damage!).

{{NOTE|The "disengaged" mode has a different behaviour on ThinkPad {{A31}} than that described above. As above, the fan speed increases beyond the levels of the regular 0-7 speed settings. However, the speed increase is fairly instantaneous (the change being as fast as the transition between any other two speed levels, except 0 (off) which seems faster, i.e. immediate); and the fan speed reading is ''continuously'' available while in "disengaged" mode. In the {{A31}}, the speed reaches about 4000 RPM as listed in the table below.}}

After boot, the HFSP register may not reflect the true state of the EC (on some models it reads 0x07 even though the EC is actually in automatic mode).

{{HINT|Apparently the [[Problem with fan noise|pulsing fan noise]] experienced by some users can be cured by repeatedly running 2-4 seconds of manual control followed by 0.5-1 seconds of disengaged mode. The pulse occurs when the the embedded controller computes the fan speed and adjusts the fan voltage adaptively every few seconds (~4.8sec for the ThinkPad T43); the aforementioned mode switching doesn't give it a chance to do so. One of the [[ACPI fan control script#Variable speed control scripts|ACPI fan control scripts]] implements this solution.}}

==Supported models==

The above was successfully tested on the following models:

* ThinkPad {{T60}} (fan levels RPM: 1-2 = 3000-3100, 3-5 = ~3600, 6-7 = ~4500)
* ThinkPad {{T43}}, {{T43p}} (fan levels RPM: 1-2 = ~3300, 3-5 = ~4100, 6-7 = ~4700; disengaged mode works)
* ThinkPad {{T42}}, {{T42p}} (fan levels RPM: 1-2 = ~2900, 3-5 = ~3700, 6-7 = ~4700; disengaged mode works at ~5200)
* ThinkPad {{T41}}, {{T41p}} (fan levels RPM: 1-2 = ~2980, 3-5 = ~3500, 6-7 = ~4050; disengaged mode works at ~5100)
* ThinkPad {{T40}} (fan levels RPM: 1-2 = ~2950, 3-5 = ~3600, 6-7 = ~4050)
* ThinkPad {{T30}}
* ThinkPad {{T22}}
* ThinkPad {{T23}} (low speed = ~2200, medium and maximum speed = ~4800; disengaged mode works at ~5800)
* ThinkPad {{R52}}
* ThinkPad {{R50}} (highest manual level is 3; disengage mode works and reaches much higher RPM)
* ThinkPad {{R50p}} (disengaged mode works at ~5100)
* ThinkPad {{R51}} (level 0 = off, level 1-2 = ~3150, level 3-5 = ~3350, level 6 = ~3750, disengaged = ~5100)
* ThinkPad {{X30}} (level 0 = off, low = ~3900, medium = ~4200, maximum = ~4650, disengaged = ~5900)
* ThinkPad {{X31}}
* ThinkPad {{X40}}
* ThinkPad {{X41T}}
* ThinkPad {{Z60t}} (fan levels RPM: 1-2 = ~1700, 3-5 = ~2800, 6-7 = ~3500)
* ThinkPad {{Z60m}} (fan levels like Z60t)
* ThinkPad {{Z61m}}
* ThinkPad {{X60}}
* ThinkPad {{A31}} (fan levels RPM: 0 = off, 1-2 = ~3280-3380 (!), 3-5 = ~3200, 6-7 = ~3380, "disengaged" = ~4000 (see NOTE above))
Probably other models are supported too (please update this page if you confirm this).

==Models using a different interface==

The following models also work, use a different access method which supported (only) via the {{path|/proc/acpi/ibm/fan}} of [[ibm-acpi]]. No need for patching.

* ThinkPad {{600E}}, {{600X}}, {{770E}}, {{770X}} (these use a different fan control interface)

==Unsupported models==

* ThinkPad {{560}} (these models don't have a fan)

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How to control fan speed