How-to written and screenshots taken on 2021 October 54 min read

## Introduction

What started as a project to run "some crypto applications" grew into something much bigger, but also more useful. I learned a tremendous amount about virtual machines, lxc containers and Proxmox. And although I'm just scratching the surface and I don't actually understand it, I know how to do some things. I'll write them down here, partly for myself, but also for you in hopes it will save one of us a lot of time and frustration.

## The problem

The Supermicro X9SCM mainboard used in my first server has 4 PWM fan connections that are normally controlled through the BIOS. This works perfectly with the case fans I installed in the front of the chassis. However, the fan on the Artic Freezer i32 CPU cooler I installed doesn't rotate when the mainboard (BIOS) decides the fan speed should be "low" ("a PWM fan that starts up at a higher load (40% PWM)").

This makes the CPU temperatures rise unnecessarily high, but can be fixed by letting the OS control the fan speed instead of the mainboard. On Ubuntu/Debian (Proxmox) this can be achieved by installing the lm-sensors package to read the CPU temperature data and fancontrol to control the fan speeds.

## Installation

1. Open a shellsession session to the server and login.

2. Install the lm-sensors and fancontrol packages.

apt updateapt install lm-sensors fancontrol
3. Configure lm-sensors as follows:

sensors-detect

Answer YES (y) to all YES/no questions. Be careful if you have a different mainboard. I read that it might give problems if non-existing sensors are being read.

4. At the end of sensors-detect, a list of modules that need to be loaded will be displayed. Type yes or y to have sensors-detect insert those modules into /etc/modules.

5. Load the added modules. This will read the changes you made to /etc/modules in the previous step, and insert the new modules into the kernel.

service kmod start
6. Now configure fancontrol.

pwmconfig

This script will stop each fan for a few seconds to find out which fans can be controlled by which PWM handle. For me only one channel was found as the case fans do not use PWM.

##### Error

If you get an error /usr/sbin/pwmconfig: There are no pwm-capable sensor modules installed, first try to reboot your machine (that solved it for me). If that doesn't work, look at the last 3 sources at the bottom of this post.

7. You will have to specify what sensors to use to link the fanspeed to temperature changes. For the CPU fan make sure to use a sensor that measures your core CPU temperature to base the fan speed on.

This is a bit tricky as the sensor is named differently in fancontrol and lm-sensors. I ran sensors in another shellsession to help me find the right sensor. In my case the CPU temperature sensor coretemp-isa-0000 was named at hwmon1 in fancontrol, so I took hwmon1/temp1_input to correlate the fanspeed to the temperature.

Now run through the prompts and save the changes to the default location. Optionally you can make adjustments to fine-tune /etc/fancontrol, but I took all the default values. Apply your changes by restarting the fancontrol service.

service fancontrol restart
8. To make the fancontrol service run automatically at system startup run:

service fancontrol start