# lm_sensors

Related articles

- Fan speed control
- hddtemp
- monitorix

lm_sensors (Linux monitoring sensors) is a free and open-source application that provides tools and drivers for monitoring temperatures, voltage, and fans. This document explains how to install, configure, and use lm_sensors.

## Installation

Install the lm_sensors package.

Note: More documentation is at the GitHub repository. In the future these may be installed, see FS#48354.

## Setup

Use sensors-detect as root to detect and generate a list of kernel modules:

Warning: Do not use anything other than the default options (by just hitting `Enter`), unless you know exactly what you are doing. See #Laptop Screen issues after running sensors-detect.

    # sensors-detect

It will ask to probe for various hardware. The "safe" answers are the defaults, so just hitting `Enter` to all the questions will generally not cause any problems. This will create the `/etc/conf.d/lm_sensors` configuration file which is used by `lm_sensors.service` to automatically load kernel modules on boot.

When the detection is finished, a summary of the probes is presented.

Example:

    # sensors-detect

    This program will help you determine which kernel modules you need
    to load to use lm_sensors most effectively. It is generally safe
    and recommended to accept the default answers to all questions,
    unless you know what you're doing.

    Some south bridges, CPUs or memory controllers contain embedded sensors.
    Do you want to scan for them? This is totally safe. (YES/no):
    Module cpuid loaded successfully.
    Silicon Integrated Systems SIS5595...                       No
    VIA VT82C686 Integrated Sensors...                          No
    VIA VT8231 Integrated Sensors...                            No
    AMD K8 thermal sensors...                                   No
    AMD Family 10h thermal sensors...                           No

    ...

    Now follows a summary of the probes I have just done.
    Just press ENTER to continue:

    Driver `coretemp':
      * Chip `Intel digital thermal sensor' (confidence: 9)

    Driver `lm90':
      * Bus `SMBus nForce2 adapter at 4d00'
        Busdriver `i2c_nforce2', I2C address 0x4c
        Chip `Winbond W83L771AWG/ASG' (confidence: 6)

    Do you want to overwrite /etc/conf.d/lm_sensors? (YES/no):
    ln -s '/usr/lib/systemd/system/lm_sensors.service' '/etc/systemd/system/multi-user.target.wants/lm_sensors.service'
    Unloading i2c-dev... OK
    Unloading cpuid... OK

Note: A systemd service is automatically enabled if users answer YES when asked about generating `/etc/conf.d/lm_sensors`. Answering YES also automatically starts the service.

## Running sensors

Example running `sensors`:

    $ sensors

    coretemp-isa-0000
    Adapter: ISA adapter
    Core 0:       +35.0°C  (crit = +105.0°C)
    Core 1:       +32.0°C  (crit = +105.0°C)

    w83l771-i2c-0-4c
    Adapter: SMBus nForce2 adapter at 4d00
    temp1:        +28.0°C  (low  = -40.0°C, high = +70.0°C)
                           (crit = +85.0°C, hyst = +75.0°C)
    temp2:        +37.4°C  (low  = -40.0°C, high = +70.0°C)
                           (crit = +110.0°C, hyst = +100.0°C)

### Reading SPD values from memory modules (optional)

To read the SPD timing values from memory modules, install the i2c-tools package. Once installed, load the `eeprom` kernel module.

    # modprobe eeprom

Finally, view memory information with `decode-dimms`.

Here is partial output from one machine:

    # decode-dimms

    Memory Serial Presence Detect Decoder
    By Philip Edelbrock, Christian Zuckschwerdt, Burkart Lingner,
    Jean Delvare, Trent Piepho and others

    Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/0-0050
    Guessing DIMM is in                             bank 1

    ---=== SPD EEPROM Information ===---
    EEPROM CRC of bytes 0-116                       OK (0x583F)
    # of bytes written to SDRAM EEPROM              176
    Total number of bytes in EEPROM                 512
    Fundamental Memory type                         DDR3 SDRAM
    Module Type                                     UDIMM

    ---=== Memory Characteristics ===---
    Fine time base                                  2.500 ps
    Medium time base                                0.125 ns
    Maximum module speed                            1066MHz (PC3-8533)
    Size                                            2048 MB
    Banks x Rows x Columns x Bits                   8 x 14 x 10 x 64
    Ranks                                           2
    SDRAM Device Width                              8 bits
    tCL-tRCD-tRP-tRAS                               7-7-7-33
    Supported CAS Latencies (tCL)                   8T, 7T, 6T, 5T

    ---=== Timing Parameters ===---
    Minimum Write Recovery time (tWR)               15.000 ns
    Minimum Row Active to Row Active Delay (tRRD)   7.500 ns
    Minimum Active to Auto-Refresh Delay (tRC)      49.500 ns
    Minimum Recovery Delay (tRFC)                   110.000 ns
    Minimum Write to Read CMD Delay (tWTR)          7.500 ns
    Minimum Read to Pre-charge CMD Delay (tRTP)     7.500 ns
    Minimum Four Activate Window Delay (tFAW)       30.000 ns

    ---=== Optional Features ===---
    Operable voltages                               1.5V
    RZQ/6 supported?                                Yes
    RZQ/7 supported?                                Yes
    DLL-Off Mode supported?                         No
    Operating temperature range                     0-85C
    Refresh Rate in extended temp range             1X
    Auto Self-Refresh?                              Yes
    On-Die Thermal Sensor readout?                  No
    Partial Array Self-Refresh?                     No
    Thermal Sensor Accuracy                         Not implemented
    SDRAM Device Type                               Standard Monolithic

    ---=== Physical Characteristics ===---
    Module Height (mm)                              15
    Module Thickness (mm)                           1 front, 1 back
    Module Width (mm)                               133.5
    Module Reference Card                           B

    ---=== Manufacturer Data ===---
    Module Manufacturer                             Invalid
    Manufacturing Location Code                     0x02
    Part Number                                     OCZ3G1600LV2G

    ...

## Using Sensor Data

### Graphical Front-ends

There are a variety of front-ends for sensors data.

- conky - Conky is an advanced, highly configurable system monitor for X based on torsmo
- xsensors - X11 interface to lm_sensors
- psensorAUR - GTK+ application for monitoring hardware sensors, including temperatures and fan speeds. Monitors motherboard and CPU (using lm-sensors), Nvidia GPUs (using XNVCtrl), and harddisks (using hddtemp or libatasmart).

For specific Desktop environments:

- sensors-applet - applet for the GNOME Panel to display readings from hardware sensors, including CPU temperature, fan speeds and voltage readings.
- plasma5-applets-thermal-monitor-gitAUR - Is an example of the widgets available for KDE desktop.
- sensors-lxpanel-pluginAUR -- A lm_sensors plugin for the LXDE panel. lxpanel also includes a simple 'Temperature Monitor' plugin.
- xfce4-sensors-plugin - A lm_sensors plugin for the Xfce panel

### sensord

There is an optional daemon called sensord (included with the lm_sensors package) which can log data to a round robin database (rrd) and later visualize graphically. See the sensord man page for details.

## Tips and Tricks

### Adjusting Values

In some cases, the data displayed might be incorrect or users may wish to rename the output. Use cases include:

- Incorrect temperature values due to a wrong offset (i.e. temps are reported 20 °C higher then actual).
- Users wish to rename the output of some sensors.
- The cores might be displayed in an incorrect order.

All of the above (and more) can be adjusted by overriding the package provides settings in `/etc/sensors3.conf` by creating `/etc/sensors.d/foo` wherein any number of tweaks will override the default values. It is recommended to rename 'foo' to the motherboard brand and model but this naming nomenclature is optional.

Note: Do not edit /etc/sensors3.conf directly since package updates will overwrite any changes thus losing them.

#### Example 1. Adjusting Temperature Offsets

This is a real example on a Zotac ION-ITX-A-U motherboard. The coretemp values are off by 20 °C (too high) and are adjusted down to Intel specs.

    $ sensors

    coretemp-isa-0000
    Adapter: ISA adapter
    Core 0:       +57.0°C  (crit = +125.0°C)
    Core 1:       +55.0°C  (crit = +125.0°C)
    ...

Run `sensors` with the `-u` switch to see what options are available for each physical chip (raw mode):

    $ sensors -u

    coretemp-isa-0000
    Adapter: ISA adapter
    Core 0:
      temp2_input: 57.000
      temp2_crit: 125.000
      temp2_crit_alarm: 0.000
    Core 1:
      temp3_input: 55.000
      temp3_crit: 125.000
      temp3_crit_alarm: 0.000
    ...

Create the following file overriding the default values:

    /etc/sensors.d/Zotac-IONITX-A-U

    chip "coretemp-isa-0000"
      label temp2 "Core 0"
      compute temp2 @-20,@-20

      label temp3 "Core 1"
      compute temp3 @-20,@-20

Now invoking `sensors` shows the adjust values:

    $ sensors

    coretemp-isa-0000
    Adapter: ISA adapter
    Core 0:       +37.0°C  (crit = +105.0°C)
    Core 1:       +35.0°C  (crit = +105.0°C)
    ...

#### Example 2. Renaming Labels

This is a real example on an Asus A7M266. The user wishes more verbose names for the temperature labels 'temp1' and 'temp2':

    $ sensors

    as99127f-i2c-0-2d
    Adapter: SMBus Via Pro adapter at e800
    ...
    temp1:        +35.0°C  (high =  +0.0°C, hyst = -128.0°C)
    temp2:        +47.5°C  (high = +100.0°C, hyst = +75.0°C)
    ...

Create the following file to override the default values:

    /etc/sensors.d/Asus_A7M266

    chip "as99127f-*"
      label temp1 "Mobo Temp"
      label temp2 "CPU0 Temp"

Now invoking `sensors` shows the adjust values:

    $ sensors

    as99127f-i2c-0-2d
    Adapter: SMBus Via Pro adapter at e800
    ...
    Mobo Temp:        +35.0°C  (high =  +0.0°C, hyst = -128.0°C)
    CPU0 Temp:        +47.5°C  (high = +100.0°C, hyst = +75.0°C)
    ...

#### Example 3. Renumbering Cores for Multi-CPU Systems

This is a real example on an HP Z600 workstation with dual Xeons. The actual numbering of physical cores is incorrect: numbered 0, 1, 9, 10 which is repeated into the second CPU. Most users expect the core temperatures to report out in sequential order, i.e. 0,1,2,3,4,5,6,7.

    $ sensors

    coretemp-isa-0000
    Adapter: ISA adapter
    Core 0:       +65.0°C  (high = +85.0°C, crit = +95.0°C)
    Core 1:       +65.0°C  (high = +85.0°C, crit = +95.0°C)
    Core 9:       +66.0°C  (high = +85.0°C, crit = +95.0°C)
    Core 10:      +66.0°C  (high = +85.0°C, crit = +95.0°C)

    coretemp-isa-0004
    Adapter: ISA adapter
    Core 0:       +54.0°C  (high = +85.0°C, crit = +95.0°C)
    Core 1:       +56.0°C  (high = +85.0°C, crit = +95.0°C)
    Core 9:       +60.0°C  (high = +85.0°C, crit = +95.0°C)
    Core 10:      +61.0°C  (high = +85.0°C, crit = +95.0°C)
    ...

Again, run `sensors` with the `-u` switch to see what options are available for each physical chip:

    $ sensors -u coretemp-isa-0000

    coretemp-isa-0000
    Adapter: ISA adapter
    Core 0:
      temp2_input: 61.000
      temp2_max: 85.000
      temp2_crit: 95.000
      temp2_crit_alarm: 0.000
    Core 1:
      temp3_input: 61.000
      temp3_max: 85.000
      temp3_crit: 95.000
      temp3_crit_alarm: 0.000
    Core 9:
      temp11_input: 62.000
      temp11_max: 85.000
      temp11_crit: 95.000
    Core 10:
      temp12_input: 63.000
      temp12_max: 85.000
      temp12_crit: 95.000

    $ sensors -u coretemp-isa-0004

    coretemp-isa-0004
    Adapter: ISA adapter
    Core 0:
      temp2_input: 53.000
      temp2_max: 85.000
      temp2_crit: 95.000
      temp2_crit_alarm: 0.000
    Core 1:
      temp3_input: 54.000
      temp3_max: 85.000
      temp3_crit: 95.000
      temp3_crit_alarm: 0.000
    Core 9:
      temp11_input: 59.000
      temp11_max: 85.000
      temp11_crit: 95.000
    Core 10:
      temp12_input: 59.000
      temp12_max: 85.000
      temp12_crit: 95.000
    ...

Create the following file overriding the default values:

    /etc/sensors.d/HP_Z600

    chip "coretemp-isa-0000"
      label temp2 "Core 0"
      label temp3 "Core 1"
      label temp11 "Core 2"
      label temp12 "Core 3"

    chip "coretemp-isa-0004"
      label temp2 "Core 4"
      label temp3 "Core 5"
      label temp11 "Core 6"
      label temp12 "Core 7"

Now invoking `sensors` shows the adjust values:

    $ sensors

    coretemp-isa-0000
    Adapter: ISA adapter
    Core0:        +64.0°C  (high = +85.0°C, crit = +95.0°C)
    Core1:        +63.0°C  (high = +85.0°C, crit = +95.0°C)
    Core2:        +65.0°C  (high = +85.0°C, crit = +95.0°C)
    Core3:        +66.0°C  (high = +85.0°C, crit = +95.0°C)

    coretemp-isa-0004
    Adapter: ISA adapter
    Core4:        +53.0°C  (high = +85.0°C, crit = +95.0°C)
    Core5:        +54.0°C  (high = +85.0°C, crit = +95.0°C)
    Core6:        +59.0°C  (high = +85.0°C, crit = +95.0°C)
    Core7:        +60.0°C  (high = +85.0°C, crit = +95.0°C)
    ...

### Automatic lm_sensors Deployment

Users wishing to deploy lm_sensors on multiple machines can use either of the following:

1. Accept defaults to questions:

    # sensors-detect --auto

2. Override defaults and answer YES to all questions:

     # yes | sensors-detect

## Troubleshooting

### K10Temp Module

Some K10 processors have issues with their temperature sensor. From the kernel documentation (`linux-<version>/Documentation/hwmon/k10temp`):

  All these processors have a sensor, but on those for Socket F or AM2+, the sensor may return inconsistent values (erratum 319). The driver will refuse to load on these revisions unless users specify the `force=1` module parameter.

  Due to technical reasons, the driver can detect only the mainboard's socket type, not the processor's actual capabilities. Therefore, users of an AM3 processor on an AM2+ mainboard, can safely use the `force=1` parameter.

On affected machines the module will report "unreliable CPU thermal sensor; monitoring disabled". Users which to force it can:

    # rmmod k10temp
    # modprobe k10temp force=1

Confirm that the sensor is in fact valid and reliable. If it is, can edit `/etc/modprobe.d/k10temp.conf` and add:

    options k10temp force=1

This will allow the module to load at boot.

### Sensors not working since Linux 2.6.31

This article or section is out of date.

Reason: kernel 2.6 references (Discuss in Talk:Lm sensors#kernel 2.6 workaround)

A change in version 2.6.31 has made some sensors stop working. See this FAQ entry for a detailed explanation and for some example errors. In most cases the information is still accessible via other modules (e.g. via ACPI modules) for the hardware in question. Many utilities and monitors (e.g. `/usr/bin/sensors`) can gather information from either source. Where possible, this is the preferred solution.

Warning: The following workaround is risky and has the potential to damage your hardware. The change in 2.6.31 is not a bug, but a fix to remove that risk. Consult the aforementioned FAQ entry for details.

If you want to restore pre-2.6.31-behaviour, add the following kernel parameters:

    acpi_enforce_resources=lax

### Gigabyte GA-J1900N-D3V

The motherboard use the ITE IT8620E chip (useful also to read voltages, mainboard temp, fan speed). As of October 2014, lm_sensors has no driver support for chip ITE IT8620E [1] [2]. lm_sensors developers had a report that the chip is somewhat compatible with the IT8728F for the hardware monitoring part. However, as of August 2016, [3] lists the IT8620E as supported.

You can load the module at runtime with modprobe:

    $ modprobe it87 force_id=0x8728

Or you can load the modules during boot process by creating the following two files:

    /etc/modules-load.d/it87.conf

    it87

    /etc/modprobe.d/it87.conf

    options it87 force_id=0x8603

Once the module is loaded you can use the sensors tool to probe the chip.

Now you can also use fancontrol to control the speedsteps of your case fan.

### Laptop Screen issues after running sensors-detect

This is caused by lm-sensors messing with the Vcom values of the screen while probing for sensors. It has been discussed and solved at the forums already: https://bbs.archlinux.org/viewtopic.php?id=193048 However, make sure to read through the thread carefully before running any of the suggested commands.

Categories:

- Status monitoring and notification
- CPU

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