Methods to reduce or eliminate fan noise

General

In this section, I will address one of the two main causes of annoying noise that our PC makes. The other is hard drive noise, to which I have dedicated a separate section. Since no PC can survive for long without sufficient cooling, and completely passively cooled PCs are probably pure exotics that should only make up a tiny fraction of all PCs, it's almost certain that your PC has a couple of of fans installed and that they will also be responsible for a large portion of the total noise, which your PC will give off. From that it follows naturally that getting the fans in your PC to operate more silently has a large potential to make your PC MUCH more silent or — ideally — turn your PC at least in certain scenarios completely inaudible.

The Cause

Fan noise is caused both by friction within the bearings and directly by excitation of the air molecules by the turbulence on the rotor blades. In addition, case fans can also introduce vibrations directly into the housing. Other than for hard drives, for which this component is the major contributor of noise, the excitation of the PC case by the fans plays a rather subordinate role. The task of fans in your PC is to guarantee the airflow necessary for cooling the installed components. The faster the fans rotate, the greater the airflow. Unfortunately, this is not only true for the airflow, but also for the fan noise, which also gets louder with increased fan speed. Therefore it is necessary to find a compromise between 'acceptably quiet' and 'still fast enough for sufficient cooling'. Since larger fans have to run significantly slower to produce the same airflow, you should make sure to purchase the largest possible fans that will fit in your existing case. Or, if even the purchase of a new case is pending, let the size of the fans you can mount into it also play a role in your purchasing decision and select a case in which you can install a sufficient amount of large fans.
A side note in terms of psycho-acoustics: the fan noise caused by changing fan speeds is perceived by us humans as much more annoying than a constant, but perhaps slightly louder louder noise of faster rotating fans.

The Remedy

Before any other measure you should first make sure that the fans can actually do their job. Usually overt time there accumulates quite a lot of dust inside your PC, especially in PCs of pet owners, to at least hinder smaller fans in their work. Occasionally, it also happens with older fans that they emit a humming noise. This is the result of a defective bearing and the only real remedy is to replace the affected fan. However, a change of the installation position can also help to operate the fan without this humming for a while. (so e.g. with a fan at the housing back by exchange with one mounted on the top).

As already described several times, the annoying fan noise is proportional to the fan speed. This means that by reducing fan speed, you have the greatest potential to reduce loud operating noise from an existing system and turn it into a quiet PC. Of course, it is important to keep the actual task of the fans in mind. They have to provide the airflow necessary for cooling the components and therefore when reducing fan speeds to reduce fan noise, you also at the same time have to monitor the temperatures of all components. Ideal are programs such as Argus Monitor, which can perform both tasks simultaneously, i.e. control the speeds of all fans, but also display the temperatures and also issue a warning if the temperature of a component reaches a critical threshold value. Of course, the optimal solution is if you can can directly control the fans depending on the temperature of the components.

A basic option for fan control is usually available directly in the BIOS of the motherboard. The disadvantage of this solution is that usually only very basic control options are available and that one has to restart the PC in order to change the control parameters. This solution can also only access sensors installed directly on the motherboard as well as in most cases also the CPU temperature. A fan control depending on the graphics card temperature or the temperature of hard drives is not possible when using your BIOS for fan control.

In addition to control via BIOS, various software programs are available that allow fan control to be more flexible and dependent on other temperature sources. The most well-known example is the freeware SpeedFan, but its development was unfortunately discontinued back in 2015. Also, the configuration is overly complicated, but if you are searching for a free solution for an older hardware, SpeedFan might be worth a look.

Another and also free option are the software products that are included with almost every motherboard. They also allow the control of all fans directly connected to the motherboard, but are usually rather confusing and inconvenient to configure and also very limited in the selection of temperature sources. Like the BIOS, they also only offer the CPU temperature as a temperature source, as well as the sensors installed on the motherboard.

The most flexible and comprehensive option for fan control via software is offered by Argus Monitor. Now, for the sake of honesty I have to confess that — as one of the two authors developing Argus Monitor in their spare time as a hobby project — I am not completely unbiased in this assessment. But objectively, there are so many points that speak for the statement that Argus Monitor is the best program for controlling PC fans, that I can say so with a clear conscience and a straight face. And when I write about fans, this includes all fans and not just case fans, but also CPU fans, fans of various AIO water cooling systems and those of graphics cards.
With Argus Monitor, you can either simply control the fan speed dependent on the temperature of any component (just select the one for which the fan in question provided the airflow for cooling. It is there fore possible, for example, to control of a case fan by using the temperature of the graphics card or the highest hard disk temperature as an input. This is something that is neither possible when using the BIOS for fan control, nor if you opt for the software that is included with the various motherboards to do this job. However, if you want to exploit the full potential, then you can also make the fan speed dependent on all the temperature sensors present in your PC. More precisely, the control of the speed can be done by an individual characteristic curve. This can then be made, if desired, dependent on e.g. the CPU temperature, but just as well on the GPU temperature, the temperatures of hard disks, the water temperature of AIO coolers or the temperatures that are various temperature sensors installed on the motherboard. Furthermore, it is possible to calculate own, synthetic temperature values from the existing temperature sensors. You can use functions such as mean value, temporal averaging, maximum, difference (e.g. from water temperature of an AIO cooling solution and ambient temperature) and more to generate an individual artificial temperature value to be used as input for the fan controller that is tailored to your own system. On top of that, other measures like smoothing us hysteresis can be used to ensure that small, short-term fluctuations in the temperatures used for control do not result in annoying speed changes.
Furthermore, with Argus Monitor it is possible to operate several controllers in parallel for each individual fan and then determine the necessary speed of a fan from the maximum value of these controllers.
In addition, the available fan profiles offer the possibility to define your own controller settings for different use cased, which can then be easily switched between at any time.

Date published: 16.06.2021

Contents

Author: Udo Rietschel

Written by Udo Rietschel

Udo is one of the two founders of Argotronic UG (haftungsbeschränkt). He is writing software since he got his hands on his first computer (a ZX Spectrum 48k back in 1988, while living in the GDR; a country that does not even exist anymore -- much like his ZX Spectrum).
Today, he is working as a software engineer, creating software for autonomous vehicles as well as Argus Monitor, which is — in his (biased) view — the best fan control software for Windows.