How to control fan speed

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This page discusses methods for controlling the system fan.

ATTENTION!
When designing fan-control applets, never ignore a valid thermal sensor.

Even if it seems to be stuck at a certain temperature, you must take that sensor into account. While it will probably make the fan spin faster than if the sensor was ignored, that's exactly what would happen when the fan is under EC control, and could very well be the reason for the "stuck" value in the first place.

Always play it safe. If a battery pack seems to want the fan to always run faster, the only safe thing to do is to make it run faster.

For Linux

NOTE!
Fan control operations are disabled by default for safety reasons.

To enable fan control, the module parameter fan_control=1 must be given to thinkpad-acpi.

For example, in Ubuntu 8.04 (Hardy Heron), add the following to /etc/modprobe.d/options: options thinkpad_acpi fan_control=1

For Debian Squeeze (testing) create /etc/modprobe.d/thinkpad_acpi.conf with: options thinkpad_acpi fan_control=1 and install the package thinkfan

Having done so, reboot and you can use the following commands to control fan speed:

# echo level 0 > /proc/acpi/ibm/fan (fan off)

# echo level 2 > /proc/acpi/ibm/fan (low speed)

# echo level 4 > /proc/acpi/ibm/fan (medium speed)

# echo level 7 > /proc/acpi/ibm/fan (maximum speed)

# echo level auto > /proc/acpi/ibm/fan (automatic - default)

# echo level disengaged > /proc/acpi/ibm/fan (disengaged)

If you receive a PERMISSION DENIED error you can use the following command syntax instead as a work-around:

# echo level 0 | sudo tee /proc/acpi/ibm/fan (fan off)

# echo level 2 | sudo tee /proc/acpi/ibm/fan (low speed)

# echo level 4 | sudo tee /proc/acpi/ibm/fan (medium speed)

# echo level 7 | sudo tee /proc/acpi/ibm/fan (maximum speed)

# echo level auto | sudo tee /proc/acpi/ibm/fan (automatic - default)

# echo level disengaged | sudo tee /proc/acpi/ibm/fan (disengaged)

Automated control scripts

An ACPI fan control script can be used 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 tp-fancontrol (download) as tp-fancontrol, make sure you've loaded thinkpad-acpi with the "fan_control=1" parameter, and run:
# ./tp-fancontrol

There is an distro independent daemon (http://launchpad.net/tp-fan/tpfand/0.94/+download/tpfand-0.94.tar.gz), written in python. Packages are available for debian based linux systems.

A GTK GUI program (packaged for Ubuntu 7.10 and 8.04) may also help.

Automated program - Simple ThinkPad Fan Control

Written by Stanko, stanko [at] mfhinc [dot] net

This is program for controlling fans speed on IBM/Lenovo ThinkPads. It is written for Linux only. This program is written in C, using GTK GUI.

You are required to have the Linux kernel with 'thinkpad-acpi' patch. You must also enable manual control for your fans. For Linux 2.6.22 and above, you must add 'fan_control=1' as a module parameter to 'thinkpad-acpi'. For example, in Debian Lenny (and Ubuntu 8.04), you must add the following to "/etc/modprobe.d/options": 

       options thinkpad_acpi fan_control=1

Having done so, reboot. Now you'll be able to use this program easily.

Here is screenshot:

Tpfc.png

and direct download (src + i386 32bit binary). Please read README.txt file included in package. [tpfc0.5.tar.gz]

I wrote this for my own personal use, and thought that it would be a good idea to release it to the world, and hope that it will be useful to someone! Feel free to send comments, bug reports or a thanks to the e-mail above.

For Windows

Shimodax's ThinkPad fan control tool offers similar functionality (see forum discussion at thinkpads.com). Source and binaries are available through the "Tp4xFanControl" project on SourceForge.

Hardware specs

The following hardware behavior was discovered experimentally by 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 thinkpad-acpi Git version.
NOTE!
The ThinkPad X61s and X61 with WWAN have a second system fan. It shares the same control register as the main fan (cannot be controlled separately), and exposes a second tachometer.

ACPI DSDT register HFSP (8 bits, offset 0x2F in the EmbeddedController 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)

Changing modes may not be immediate on all ThinkPads. Later ThinkPad models seem to take at least 5s to start responding to a fan mode change, for example.

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).

The HFSP register controls both fans at the same time in the X61/X61s.

Fan Tachometer

The embedded controller registers 0x84 (LSB), 0x85 (MSB) are the main fan tachometer, and report fan speed in RPM in everything since the A31 and maybe a little earlier. Not much is know about the tachometer in earlier models, or even whether they had one or not.

On the X61/X61s, one must select through EC register 0x31 bit 0 which fan the tachometer registers will expose (Firmware 7M). Beware: this is the same register used for brightness control in other models.

Automatic mode

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

Note that the ACPI DSDT may supplement this in some models. The X40, for example, changes the profile of speeds the automatic mode should use depending on battery status.

Manual mode

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.

Disengaged (full-speed) mode

In disengaged mode, the embedded controller does not monitor the fan speed. It "disengages" the closed-loop control function that keeps track of fan speed, and uses an open-loop control function that ramps up the fan to its maximum speed (100% duty-cycle). The end speed is not stable, but it is often much faster than the maximum speed manual and automatic modes would set the fan to.

Most newer ThinkPads take quite a while (in excess of one minute) to fully enter disengaged mode. Exiting it is much faster. The A31 acts differently, and switches to disengaged mode as fast as it switches to other modes.

For some reason, the embedded controller may stop updating the tachometer registers while entering or exiting disengaged mode in some ThinkPad firmware versions (hence the EC tachometer registers will not be updated on these models while entering/exiting disengaged mode). Once it arrives at maximum speed, or once it gets back at closed-loop cruise speed, the embedded controller starts updating the tachometer registers again. Later T models such as the T43 have this problem, while the A31 does not.

Hint:
Apparently the 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 scripts implements this solution.

Supported models

The above was successfully tested on the following models:

  • ThinkPad A31, A31p (fan levels RPM: 0 = off, 1-2 = ~3280-3380 (!), 3-5 = ~3200, 6-7 = ~3380, "disengaged" = ~4000 (see NOTE above))
  • ThinkPad R50 (highest manual level is 3; disengage mode works and reaches much higher RPM)
  • ThinkPad R50p (fan levels RPM: 0 = off, 1-2 = ~3200, 3-5 = ~3500-3600, 6-7 = ~3700-3800, disengaged = ~5300)
  • ThinkPad R51 (fan levels RPM: 0 = off, 1-2 = ~3150, 3-5 = ~3350, 6 = ~3750, disengaged = ~5100)
  • ThinkPad R51e (fan levels RPM: 0 = off, 1-2 = ~3300, 3-5 = ~3800, 6 = ~4150, disengaged = ~5100)
  • ThinkPad R52 (fan levels RPM: 0 = off, 1-2 = ~3350, 3-5 = ~3650, 6 = ~4250, disengaged = ~5245)
  • ThinkPad R60 (fan levels RPM: 0 = off, 1-1 = ~2650, 3-5 = ~3300, 6-7 = ~3950, disengaged = ~4800)
  • ThinkPad R60e
  • ThinkPad R61i (fan levels RPM: 0 = off, 1 = 2689, 2 = 2729, 3 = 3059, 4 = 3047, 5 = 3051, 6 = 3515, 7 = 3468, full-speed/disengaged = 4119~4200)mod.#7650-D7G@+/-2yr.used
  • ThinkPad T22
  • ThinkPad T23
    • (low speed = ~2200, medium and maximum speed = ~4800; disengaged mode works at ~5800)
    • (fan levels = ~RPM: 0 = 0; 1,2 = ~2200; 3,4,5,6,7 = ~4900; disengaged,full-speed = ~6331)
  • ThinkPad T30
  • ThinkPad T40 (fan levels RPM: 1-2 = ~2950, 3-5 = ~3600, 6-7 = ~4050; disengaged = ~5400)
  • ThinkPad T41, T41p (fan levels RPM: 1-2 = ~2980, 3-5 = ~3500, 6-7 = ~4050; disengaged mode works at ~5100)
  • ThinkPad T410i (fan levels RPM: 0 = off, 1 = ~1950, 2 = ~3575, 3-4 = ~3700, 5-6 = ~3825, 7 = ~4525; disengaged = ~5450; only Linux-tested with tpfc0.5)
  • ThinkPad T42, T42p (fan levels RPM: 1-2 = ~2900, 3-5 = ~3700, 6-7 = ~4700; disengaged mode works at ~5200)
  • ThinkPad T43, T43p (fan levels RPM: 1-2 = ~3300, 3-5 = ~4100, 6-7 = ~4700; disengaged mode works at ~6450)
  • ThinkPad T60 (fan levels RPM: 1-2 = 3000-3100, 3-5 = ~3600, 6-7 = ~4500; disengaged mode works at ~5500)
  • ThinkPad T61 (fan levels RPM: 0 = off, 1-2 = ~2980, 3-5 = ~3330, 6-7 = ~3760; disengaged mode works at ~4500)
  • ThinkPad W500 (fan levels RPM: 0=off, 1-2 = 1900, 3-5 = ~3000, 6-7 = ~3500; disengaged mode works at ~5100)
  • ThinkPad X30 (level 0 = off, low = ~3900, medium = ~4200, maximum = ~4650, disengaged = ~5900)
  • ThinkPad X31 (fan levels RPM: 0 = off, 1-2 = ~2850, 3-5 = ~3450, 6 = ~4050, 7 = ~4150; disengaged mode works at ~4975)
  • ThinkPad X40
  • ThinkPad X41
  • ThinkPad X41 Tablet
  • ThinkPad X60 (fan levels RPM: 7 = ~3700, disengaged ~4700)
  • ThinkPad X61 (fan levels RPM: 1-2 = ~3400, 3-5 = ~3800, 6-7 = ~4500, disengaged = ~6700)
  • ThinkPad X61s (fan levels RPM: 0 = off, 1-2 = ~3800, 3-5 = ~4500, 6-7 = ~4800, disengaged = ~4800) (though fancontrol can keep it at 2500rpm...)
  • ThinkPad Z60t, Z60m (fan levels RPM: 1-2 = ~1700, 3-5 = ~2800, 6-7 = ~3500)
  • ThinkPad Z61m
  • Thinkpad Z61p (fan levels 0-7, auto, disengaged; enable, disable; watchdog (untested))

Probably other models are supported too (please update this page if you confirm this; maintain some ordering too).

Models using a different interface

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

Unsupported models

  • ThinkPad 560 (these models don't have a fan)
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