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.
Install the lm_sensors package.
Use sensors-detect as root to detect and generate a list of kernel modules:
Enter), unless you know exactly what you are doing. See #Laptop screen issues after running 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.
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
/etc/conf.d/lm_sensors. Answering YES also automatically starts the service.
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)
Adding DIMM temperature sensors
To find the temperature sensors of DIMMs, install the i2c-tools package. Once installed, load the
i2c-dev kernel module.
# modprobe i2c_dev
To show all the columns, use i2cdetect as root:
# i2cdetect -l
i2c-2 smbus SMBus PIIX4 adapter port 2 at 0b00 SMBus adapter i2c-2 smbus SMBus PIIX4 adapter port 1 at 0b20 SMBus adapter i2c-0 smbus SMBus PIIX4 adapter port 0 at 0b00 SMBus adapter
Otherwise, its output will appear as follows:
i2c-2 unknown SMBus PIIX4 adapter port 2 at 0b00 N/A i2c-2 unknown SMBus PIIX4 adapter port 1 at 0b20 N/A i2c-0 unknown SMBus PIIX4 adapter port 0 at 0b00 N/A
In the following example, RAM sticks are connected to the bus
SMBus 0. The i2cdetect command will show the devices that are connected to the bus. The
-y 0 argument uses the
i2c-0 smbus. Check other buses if needed.
# i2cdetect -y 0
0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- 0c -- -- -- 10: 10 -- -- -- -- -- -- -- 18 19 -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- 36 -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4f 50: 50 51 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- 77
RAM SPD's (serial presence detect) start from address
0x50 and RAM temperature sensors start from
0x18 at same bus. In this example, there are 2 DIMMs available. The address
0x19 are the DIMMs temperature sensors.
To read the temperatures of RAM sticks, we need the
jc42 kernel module loaded. You need to tell the module which addresses to use. This process consists of writing the
smbus_path. For example:
# modprobe jc42 # echo jc42 0x18 > /sys/bus/i2c/devices/i2c-0/new_device # echo jc42 0x19 > /sys/bus/i2c/devices/i2c-0/new_device
After that your ram sticks temperature will be visible:
jc42-i2c-0-19 Adapter: SMBus PIIX4 adapter port 0 at 0b00 temp1: +50.7°C (low = +0.0°C) ALARM (HIGH, CRIT) (high = +0.0°C, hyst = +0.0°C) (crit = +0.0°C, hyst = +0.0°C) jc42-i2c-0-18 Adapter: SMBus PIIX4 adapter port 0 at 0b00 temp1: +51.8°C (low = +0.0°C) ALARM (HIGH, CRIT) (high = +0.0°C, hyst = +0.0°C) (crit = +0.0°C, hyst = +0.0°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
Here is partial output from one machine:
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
There are a variety of front-ends for sensors data.
- psensor — 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).
- xsensors — X11 interface to lm_sensors.
For specific Desktop environments:
- Freon (GNOME Shell extension) — Extension for displaying CPU temperature, disk temperature, video card temperature , voltage and fan RPM in GNOME Shell.
- GNOME Sensors Applet — Applet for the GNOME Panel to display readings from hardware sensors, including CPU temperature, fan speeds and voltage readings.
- lm-sensors (LXPanel plugin) — Monitor temperature/voltages/fan speeds in LXDE through lm-sensors.
- MATE Sensors Applet — Display readings from hardware sensors in your MATE panel.
- Sensors (Xfce4 panel plugin) — Hardware sensors plugin for the Xfce panel.
- Thermal Monitor (Plasma 5 applet) — KDE Plasma applet for monitoring CPU, GPU and other available temperature sensors.
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(8) man page for details.
Tips and tricks
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 than 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.
/etc/sensors3.confdirectly 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.
coretemp-isa-0000 Adapter: ISA adapter Core 0: +57.0°C (crit = +125.0°C) Core 1: +55.0°C (crit = +125.0°C) ...
sensors with the
-u switch to see what options are available for each physical chip (raw mode). If some of the raw labels you are presented seem not to be configurable, look at the
/sys/class/hwmon directory tree. Each device mentioned there has a
name file, which can be used to match the device it is referring to. And then try the labels referred to by that directory.
$ 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:
chip "coretemp-isa-0000" label temp2 "Core 0" compute temp2 @-20,@-20 label temp3 "Core 1" compute temp3 @-20,@-20
sensors shows the adjust values:
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
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:
chip "as99127f-*" label temp1 "Mobo Temp" label temp2 "CPU0 Temp"
sensors shows the adjust values:
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.
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) ...
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:
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"
sensors shows the adjust values:
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 the following to accept the defaults to all questions:
# sensors-detect --auto
S.M.A.R.T. drive temperature
Since kernel 5.6 the
drivetemp module will report SATA/SAS temperature through hwmon, but
sensors-detect does not automatically detect this so the module must be manually loaded.
# modprobe drivetemp
You should now see entries similar to this in your
drivetemp-scsi-1-0 Adapter: SCSI adapter temp1: +33.0°C drivetemp-scsi-2-0 Adapter: SCSI adapter temp1: +32.0°C (low = +0.0°C, high = +70.0°C) (crit low = +0.0°C, crit = +70.0°C) (lowest = +29.0°C, highest = +41.0°C)
You can now load the module at boot. Alternatively, manually add it to the
HWMON_MODULES line of
/etc/conf.d/lm-sensors. Do note it will not be added automatically when
sensors-detect will be allowed to write this file again.
Some K10 processors have issues with their temperature sensor. See the k10temp documentation for more information.
On affected machines the module will report "unreliable CPU thermal sensor; monitoring disabled". To force monitoring anyway, you can run the following:
# 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.
Asus B450M-A/A320M-K/A320M-K-BR motherboards
These motherboards use a IT8655E chip, which is not supported by the it87 kernel driver, as of Nov 2020 . However, it is supported by the upstream version of the kernel driver . The DKMS variant is contained in it87-dkms-gitAUR.
Asus B450/X399/X470 motherboards with AM4 Socket
Some recent Asus motherboards use a ITE IT8665E chip, accessing the temperature, fan and voltage sensors may require the
asus-wmi-sensors module. It is part of the mainline kernel since 5.17: load the
asus-wmi-sensors kernel module which uses the UEFI interface and may require a BIOS update on some boards .
it87 module reads the values from the chip directly, install it87-dkms-gitAUR and load the
it87 kernel module.
Asus H97/Z97/Z170/Z370i/X570/B550 motherboards
With some recent Asus motherboards, fan and voltage sensor access may require the
nct6775 kernel module to be loaded.
You may also need to add the following kernel parameter:
See https://bugzilla.kernel.org/show_bug.cgi?id=204807 for more information.
Note: Starting with Kernel 5.16 , the above kernel parameter is no longer be required for most boards and should be avoided.
Asrock Deskmini H470
The STX board of the Deskmini H470 uses a NCT6683 chip, for accessing the temperature, fan and voltage sensors the loading of
nct6683 module is required.
For proper values of the
nct6683 module have a module config file created:
options nct6683 force=1
Gigabyte B250/Z370/B450M/B560M/B660M/Z690 motherboards
Some Gigabyte motherboards use the ITE IT8686E, ITE8689 (for B560 and B660M) or ITE8689E (for Z690) chip, which is not supported by the it87 kernel driver, as of May 2019 . However, it is supported by the upstream version of the kernel driver . The DKMS variant is contained in it87-dkms-gitAUR. As with #Asus H97/Z97/Z170/Z370i/X570/B550 motherboards, a kernel parameter is required before attempting to install the module:
Furthermore, supply the id of the chip when loading the module as follows:
# modprobe it87 force_id=0x8686 or # modprobe it87 force_id=0x8689 # for B560 # modprobe it87 force_id=0x8628 # for Z690
Or you can load the module during boot process by creating the following two files:
options it87 force_id=0x8628
options it87 ignore_resource_conflict=1
Once the module is loaded you can use the sensors tool to probe the chip. Now you can also use fancontrol to control the speed step of your case fan.
Optionally installation of zenpower3-dkmsAUR may allow greater fine tuning of the motherboard's cooling system. However, it does disable the default k10temp module.
This motherboard uses 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  . 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,  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:
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.
There is currently a bug in the way the kernel handles reading the i2c bus on AMD Navi 2 GPUs. The bus currently can only be used with EEPROMs and trying to use it with other devices will cause it to fail. This can cause crashes, black screens, and even cause the card to behave oddly like unable to switch power states. Its currently advised not to scan the i2c bus if you have a Navi 2 based card. You can read more here: https://gitlab.freedesktop.org/drm/amd/-/issues/1470