How to control PC fans and tips for fan control software
At the latest when the PC is too loud, or you want to run your computer efficiently, you come into contact with the topic of fan control. In addition, modern systems have sophisticated power saving mechanisms that allow the cooling to be throttled in idle mode. Under load, z.B. when gaming, they in turn develop considerable heat. Accordingly, the fans in the system may/must also be flexible.
How to control the fans in the PC, what you have to pay attention to and which possibilities there are, we show in this guidebook.
Fan and fan control FAQ
First we clarify a few basic things. Which PC fans can be controlled, the difference between 4-pin and 3-pin fans and what to look for in fan connections on the mainboard. Keyword: PWM and voltage.
How to control a fan – PWM, DC mode, 3-pin and 4-pin
There are two common types of PC fans. Fans with a 3-pin fan connector and fans with a 4-pin connector, so-called PWM fans. The latter have the same three wires, supplemented by the fourth wire for the PWM signal. The pin assignment is as follows:
Ground – +12V – Speedometer signal – PWM
(On the following picture seen from bottom to top)
In principle, a fan only needs the first two wires (plus and minus/ground) to function. The third wire is responsible for outputting the tachometer signal to the mainboard/fan controller. The signal is only used to read the rpm, not to control it.
4-pin of a Noctua NF-F12 PWM fan
The fourth wire of PWM fans is for the PWM signal, which is used to tell the fan how fast it should rotate. PWM stands for pulse-width modulation and has nothing to do with automatic control, as is still often falsely claimed. It is only the technical realization how the fan is controlled.
be quiet! Silent Wings 3
A 4-pin PWM fan gets a constant voltage of 12V on the plus wire, i.e. the maximum for PC fans. Via the PWM signal, the electronics in the fan (PWM-IC), the power supply is switched on and off. This allows you to control how fast the fan rotates. The more often and longer the fan gets power, the faster it spins. The other way round, the slower and less often the current is applied, the lower the speed will be. Like a merry-go-round that you push frequently or rarely.
This type of control also allows manufacturers to quite accurately determine a speed range that is specified for PWM fans (z.B. 300-1500 rpm). Examples of good PWM fans with high speed range are the be quiet! Silent Wings 3 PWM (at amazon)* or the Arctic P12 PWM (at amazon)*
Can also control 3-pin fans?
Yes, but! Even a 3-pin fan, i.e. without PWM signal) can be controlled. It does not get a control signal, but you can reduce the speed by simply lowering the voltage from 12V. If there are only 9, 7 or 5V the fan rotates slower. This is also how mainboards and fan controllers do it
3-pin connection of a Fractal Design fan
How far a fan can be controlled by this is variable. Rarely do manufacturers specify the voltage range. Some fans start at 4V, others only at 7V. Sometimes there are also variations within a model.
Here PWM often has an advantage due to a larger range and the manufacturers can specify the speed range exactly.
Exception to the above mentioned fans are fans that are still connected directly to the power supply via a large Molex connector, as you sometimes find them in cheap cases. No control is possible here! One however by adapter the voltage permanently reduce.
3 pin fan to 4 pin connector and 4 pin fan to 3 pin connector, is that possible?
In principle 3-pin fans work on 4-pin connectors and vice versa, the first pins are identical. Things look different with the control. Here you have to differentiate according to the mainboards. Halay current mainboards have almost exclusively 4-pin fan connectors, but they can be switched flexibly. So they can be operated in PWM mode, or in DC mode. Depending on what kind of fan is connected, the control is realized via the fourth pin by PWM, or via the voltage. The fourth pin then remains unused.
4-pin fan connector for 3 and 4-pin fans
If the motherboard does not handle this, the picture is a bit different:
If you connect a PWM fan to a voltage controlled 3-pin connector, control is still possible. Also a PWM fan turns slower if you reduce the voltage. The speed range is then possibly limited, or. different from what you know from PWM control.
But it is not possible to control a 3-pin fan on a 4-pin connector which does not support DC mode. As explained before, there are always 12V at the 4-pin connector and the 3-pin fan does not get and understand a PWM signal – so it always turns at maximum speed.
Multiple fans on one connector and how many?
Cheap mainboards often have few fan connectors and at the latest with gaming systems or watercooling systems five, six or more fans are installed in the case. This is not a problem, because fan connections can be extended. The simplest variant is a Y-cable (at amazon)*, with which two fans are connected to one connector. These cables are also available in triplicate (at amazon)* or more – like a multiple plug for the wall socket.
Attention: The speed is only output by one fan, because the mainboard cannot read several of these signals. For this reason correct Y- resp. multiple cables on all but one connection the third pin. If you connect different fans, mine doesn’t have any information about how fast the others rotate.
4-pin cable for three fans
How many fans can be connected to one port depends on the performance of the mainboard and the consumption of the fans. Here a look in the manual and in the data sheet of the fans helps. In many cases, a motherboard connector provides 1A (12W), while the fans can be controlled in the range of 1A.5 – 3W are set up. Two or three fans on one port are usually no problem.
If you want more, you can use a hub. These offer more ports and have an additional power supply to relieve the motherboard. The Arctic HUB for PWM fans (at amazon)* controls up to 10 fans together on one connector. At the Deepcool Hub (at amazon)* also 3-pin fans can be connected, but these are not regulated.
Controlling PC fans: BIOS and fan control software
Fan control in BIOS/UEFI
Fans can already be controlled via the BIOS of the motherboards without further software. Thanks to the UEFI interface of current motherboards this is also quite comfortable. Once set, the mainboard takes care of controlling the fans without the need to have another program installed. The interfaces of the different manufacturers differ a bit, but the functions are similar.
We show this here exemplarily on the surface of a Gigabyte and an ASUS mainboard. With ASUS, you have to go into the Q-Fan configuration for detailed settings, while the fan curve can be set under "Qfan-Control". Gigabyte unites everything completely under the menu item "Smart Fan".
Fan control Gigabye BIOS/UEFI
ASUS Q-Fan Control
ASUS Q-Fan configuration
After selecting the fan port to control (1) If you have selected a hub, you can set the control mode to (2) whether it should be controlled by voltage (DC) or by PWM (see difference 3-pin/4-pin). This is also valid, if one would like to control later nevertheless rather by software! CPU fan, AiO water cooling fan and case fan can be controlled in the same way. With CPU coolers and AiOs you usually have to deal with PWM fans.
Furthermore it lets the temperature source (3) determine according to which should be controlled. The CPU fan according to the CPU temperature, the rest as desired. How suitable the offered sensors are for this, you try out yourself. Optimal would be an external sensor for the case fans of course, but not every board can do that.
The fans are controlled via the so-called fan curve (4). You define how fast the fan should rotate at a certain temperature. For example 50% at 40 degrees and 60% at 55 degrees etc. The cooler the system, the slower and vice versa. The boards offer one or more fan curves, but it’s better to configure them manually and set the system according to one’s own wishes.
Regardless of whether you control by voltage or PWM, the boards allow a percentage setting, the exact voltage value (e.g. 7V) can’t be set. What finally comes out at 50% also depends on the fan. 50% of a 2000 rpm fan doesn’t necessarily result in 1000 rpm – you have to test here.
About the calibration (5) some boards can – more or less reliably – determine the speed range.
Also interesting is the point Interval or also Step-Up/ Boost-Time (6). Here you can set a delay so that the fans don’t start up immediately after every small temperature jump. Especially with modern CPUs this prevents the constant up and down of the fans.
If after saving and restarting you get a warning message regarding the control mode. of the CPU fan are displayed, it turns too slowly. If one is sure that it works reliably, one can lower or deactivate the warning level (7).
Fan control via mainboard software
Those who want to control it under Windows need appropriate software. One possibility are the programs of the motherboard manufacturers, like Gigabyte SIV and ASUS AI Suite. Due to the integration into larger system software packages, they are quite overloaded, but basically only offer the functions of the BIOS in terms of fan control. Gigabyte additionally allows to determine the fan speed range here, unfortunately not always correctly.
ASUS AI Suite
Gigabyte SIV software
Would you like more, z.B. which control the case fans according to the graphics card temperature, this is rarely possible with them. Other software like SpeedFan is outdated. An alternative is the Argus Monitor, but it also has to be paid for.
Fan Control – modern Speedfan alternative
Here comes, in our opinion ingenious, fan control software "Fan Control" into play.
Fan Control is not only an alternative to the old Speedfan, but combines many other functions and possibilities under one neat surface.
The advantages are that besides the fans connected to the mainboard (CPU-, case-, water cooling fans) also the graphic card fans can be controlled. So there is no need to run the GPU software of the manufacturer or the MSI Afterburner.
Also, more temperature sensors can be used as a source. For example, you can control the case fans according to the graphics card.
The Fan Control software is available for free on GitHub, a donation is optional. No installation is necessary, just unzip the archive and you’re ready to go!
The interface is not as spectacular as the stylish UIs of the motherboard software, but you will quickly find your way around after a bit of familiarization.
In the upper section you can see the controllers found by the software. In our case, besides the installed graphics card, the fan connectors for the CPU fan and the case fans on the mainboard. If there controllers are detected by mistake or counted twice, you can simply hide them.
Automatic fan detection
Below, in the "Speed" section, you can see the fans and their read-out speeds. First you have to assign the appropriate fan to each controller. This can also be done automatically. If this is not correct, you can intervene manually.
If you know which controller represents which fan, you directly give it the matching name! Speed section can then be hidden. Now we have the basis for perfect fan control.
Fan control – automatic curve, manual fan curve or fixed speed?
Now it’s time for the actual fan control by creating your own curves. To do this, click on the barely overlooked +.
FanControl provides not only simple fan curves, but also different variants of them.
Sync: Synchronizes the fan with the current value of a controller.
Graph: This is the typical fan curve as known and probably most often used. Here you can fix the exact course of the fan speed depending on the temperature.
LinearHere you only select a minimum temperature and a maximum temperature between which the fan control rises linearly, i.e. evenly. At the same time you define the minimum and maximum control in percent.
Flat: A simple default to permanently control the fans at the specified value z.B. 50%.
Mix: This combines the current values of two or more fan curves. Here you can calculate the average, sum, maximum and minimum from the other fan curves.
Target: Defined idle and load temperatures serve as a trigger point for the specified speed value.
Which fan curve is the right one for you, you have to weigh up. With a fan curve of the graph type, the optimum in volume and cooling performance is possible, but also requires a certain configuration effort. You can adjust the fan behavior to your own requirements in great detail and determine how loud the computer can work and what temperatures you can accept.
Automatic curves are more convenient, simpler, but do not always behave optimally.
Once you have decided on the curve, usually probably graph, you can configure it further. First of all, you select the temperature source, i.e. according to which component you want to control the fan. Here you can choose the CPU, the installed SSDs, mainboard sensors and also the graphics card as a source. If you want the case fan in the front to supply the graphics card with fresh air, then select it as the source and set your fan curve.
Unfortunately, there is no patent recipe for the perfect fan curve. Each system is too individual for this. graphics card, processor, case, the installed fans etc. make it necessary to try it out for yourself here. Acoustically it is advantageous to avoid strong jumps. As an alternative, you look for two fixed levels that you use for idle and load, which you consider sufficient in terms of volume and cooling.
Once you have chosen and created a curve, assign it to the controller above under "Fan Curve". From now on the fan will be controlled with this curve.
On and off swelling fans, fans go on and off
Important and another strength are the configurable hysteresis and the "response time", which we already mentioned during the configuration via BIOS.
Hysteresis prevents the fans from constantly jumping back and forth, or going on and off when they are at a threshold and constantly falling below and exceeding it. You define a few degrees as a buffer, within which the fans do not change.
Example: One determines that the fans stand still below 50 degrees with the graphics card. If the fans exceed 50 degrees, they start running. If the graphics card cools down to below 50 degrees, they stop. The graphics card warms up again. The fans therefore constantly go on and off. With a hysteresis of 3 degrees, the fans would start at 50 degrees, but only stop again when 47 degrees were reached.
Response time is interesting for owners of current CPUs, especially for AMD Ryzen 3000 and AMD Ryzen 5000 processors. The CPUs sometimes have strong, very short temperature peaks even at lowest workloads z.B. when opening the browser, a program etc. This leads to the fans constantly revving up briefly and then dying down again – very annoying.
The temperature peaks are so short that it’s not necessary to let the fan react to them. With the response time you create some relaxation. The fan only reacts when the temperatures remain high over the set time. Acoustically, it’s much more pleasant and consistent.
Similar functions are also available on mainboards. Terms like "spin up/down time" or "interval" are common here. Often, however, with only very short times, which do not effectively counter the jumps.
Retrofit fan control
If you still can’t control the fans with the mainboard, you have to buy a separate fan controller. On the one hand there are internal fan controls, which you can control via your software as mentioned above. If you only want to control PWM fans, we recommend the Aqua Computer OCTO (at amazon)* controller, which offers a lot of possibilities thanks to the Aqua Suite software. We have written a test about the OCTO.
OCTO for PWM fans
Corsair Commander Pro
As an alternative with a somewhat less complex software, it’s worth taking a look at the Corsair Commander Pro (at amazon)* with the well-known iCUE software. This controls both 4-pin and 3-pin fans, and also handles RGB control. Both OCTO and Commander Pro allow to connect external temperature sensors.
If you don’t want to deal with software, you can also buy a manual fan controller. Especially simple are models with a knob z.B. Noctua NA-FC1 (at amazon)* for a 1-3 PWM fan. More elaborate are controllers with a display like the Thermaltake Commander FT (at amazon)*
Control PC fan by adapter
The PC is noisy, but control is not possible? Or don’t feel like investing time in configuration or money in the controller? In this case, adapters (at amazon)* that reduce the fan voltage and thus make the fans quieter are a good option. Of course, it should be checked whether the cooling capacity is still sufficient.
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