How Does A 4 Channel Controller Fan Work

Management of the rotational speed of a computer fan

Full belfry computer cases may contain multiple cooling fans. At the top of the case is a fan controller.

Fan control is the management of the rotational speed of an electric fan. In computers, various types of estimator fans are used to provide acceptable cooling, and different fan command mechanisms balance their cooling capacities and noise they generate. This is commonly accomplished by the motherboards having hardware monitoring circuitry, which can exist configured by the finish-user through BIOS or other software to perform fan command.^[one]

Need for fan control [edit]

As modern PCs grow more than powerful so do their requirements for electric ability. Computers emit this electrical power as heat generated past all major components. Heat production varies with system load, where periods of compute-intensive activity generate much more rut than the idle fourth dimension does.^[1]

Processors in about early x86-based computers, upward to some of the early 486s, did not need agile ventilation. Power supplies needed forced cooling, and power supply fans also circulated cooling air through the balance of the PC with the ATX standard. The byproduct of increased estrus generation is that the fan(s) need to move increasing amounts of air and thus demand to exist more than powerful. Since they must move more than air through the aforementioned surface area of space, fans volition become more noisy.

Fans installed in a PC case can produce noise levels of up to lxx dB. Since fan dissonance increases with the 5th power of the fan rotation speed,^[2] reducing revolutions per minute (RPM) past a small-scale corporeality potentially ways a large reduction in fan dissonance. This must be done charily, as excessive reduction in speed may crusade components to overheat and exist damaged.^{[ needs update ]} If done properly fan noise tin exist drastically reduced.

Fan connectors [edit]

The mutual cooling fans used in computers use standardized connectors with two to iv pins. The first two pins are e'er used to evangelize power to the fan motor, while the residuum can be optional, depending on fan design and type:

Ground – common ground
Vcc (Power) – nominally a +12 V supply, though information technology may be variable depending on fan blazon and desired fan rotation speed
Sense (or tachometer) output from fan – outputs a point that pulses twice for each revolution of the fan as a pulse train, with the signal frequency proportional to the fan speed
Control input – a pulse-width modulation (PWM) input indicate, used when the cooling fan assembly has an internal motor driver excursion. Fan assemblies with this control input provide the power to accommodate the rotational speed of the fan without irresolute the input voltage delivered to the cooling fan assembly. A variable rotation speed allows the cooling charge per unit to be adapted to meet need, quietening the fan and saving energy when full speed is not required.

The color of the wires connected to these pins varies depending on the number of connectors, simply the role of each pin is standardized and guaranteed to exist the same on any system. Cooling fans equipped with either 2- or three-pin connectors are usually designed to have a wide range of input voltages, which directly affects the rotation speed of the blades.

Types of control [edit]

Thermostatic [edit]

In this style of fan command, the fan is either on or off. Temperature inside the chassis is checked, and if an outside-of-range temperature is detected, fans are gear up to their maximum speed. When the temperature drops below a threshold once again, the fans are turned back off. This control method reduces noise issues and power requirements during periods of depression usage, but when the system is operating at capacity, the fan dissonance can go a problem again.

Linear voltage regulation [edit]

A standard cooling fan is a DC motor with blades attached. By varying the voltage input across the acceptable range for a fan, the speed of the fan will increase (to added voltage) and decrease (to reduced voltage); a faster fan ways more than air moved and thus a higher heat exchange rate. There are a few ways to perform this regulation, as described below.

Resistors [edit]

Resistors in series with a fan'south ability pin are the simplest method of reducing fan dissonance, only they add to the heat generated within the computer case. Since the voltage driblet is proportional to the current, the fan may non start. They need to be of the appropriate power rating. For variable fan control, potentiometers could be used forth with a transistor such as a MOSFET whose output voltage is controlled past the potentiometer. Information technology is possible to apply a rheostat instead.

Diodes [edit]

A diode in series with the fan will reduce the voltage being output to the fan. A silicon diode provides a relatively constant voltage drop of almost 0.seven V per diode; information sheets for a specific diode specify its voltage drop, for example the 1N4001 silicon diode's voltage drop varies from approximately 0.7 to 0.nine V as the current varies from 0.01 to ane A.^[3] The power rating should be noted and some diodes may crave cooling to operate at their rated current. The voltage driblet across the diode volition fall with temperature, causing the fan to speed up.

Like other series regulators, the diode will misemploy power equal to its voltage driblet times the current passing through it.

Voltage modification ("volt modding") [edit]

The voltage a figurer cooling fan receives is defined by the deviation between the voltage wire (+12 Five) and the footing wire (+0 Five). By connecting ane or both wires to a dissimilar voltage, the voltage the fan receives will be different from the default 12 V the fan was designed for.

Increasing the voltage^[iv] over the default 12 5 can be achieved by e.g. connecting the −12 V or −5 V power line instead of the ground wire in the fan connector, and by connecting the 5 Five power line in the +12 V input of the fan connector. Through this procedure, 10, 17 and 24 5 voltages can exist accomplished, with voltages exceeding 12 V being potentially damaging to the computer fans rated at 12 V. However, the combination of modern power supplies no longer existence required to provide a −5 V ability line and the limited power delivery capability of the −12 V line (commonly less than 1 A of current) reduces the total capacity for volt modded fans in modern systems.

Connecting the +5 V electric line to the +12 V input of the fan reduces the voltage the fan receives to +five Five. Some fans will not work at such low voltage at all, while some other fans may run at +five Five once they take started rotating at a reasonable speed.^{[ citation needed ]}

Another method of reducing the fan speed^[5] is by moving the 5 V wire in the classical Molex power connector in the place of the Footing wire going to the fan, thereby delivering +7 5 (12 V − 5 V = 7 5) to the fan. All the same, this is a potentially risky method, because +5 V PSU line is intended to source current only, not sink it, then the PSU is likely to get damaged in example of load on five V PSU line being below the load generated by 7 V fans (e.thou. when PC enters idle/sleep state). Also, the components inside the computer using +five Five ability might be exposed to over 5 5 in case of a short excursion in the fan.

Integrated or discrete linear regulators [edit]

SMSC EMC2102 rotational-speed-based fan controller with hardware thermal shutdown

Common voltage regulator ICs similar the popular LM78xx series are sometimes used to provide variable or abiding voltage to fans. When thermally bonded to the reckoner's chassis, one of these ICs can provide up to 1 A of current at a voltage of 6, 8, ix or 10 V for the LM7806, LM7808, LM7809 and LM7810, respectively.^[6] Adaptable versions similar the pop LM317 also exist; when combined with a potentiometer, these adjustable regulators let the user to vary the fan speed of several fans at currents far in excess of what a standard potentiometer could handle.^[7]

For higher currents, discrete linear regulators are relatively unproblematic to construct using a power transistor or MOSFET and a small betoken transistor or a Zener diode as a voltage reference. While discrete regulators require boosted components (a minimum of two transistors, iii resistors and a pocket-sized capacitor), they let for arbitrarily loftier currents, assuasive for the regulation of additional fans and accessories.

As with other linear regulators, the waste heat that is produced will be roughly $P = (V in - V out) I out$ .^[viii]

Pulse-width modulation [edit]

Pulse-width modulation (PWM) is a common method of controlling calculator fans. A PWM-capable fan is usually continued to a four-pivot connector (pinout: Ground, +12 V, sense, control). The sense pin is used to relay the rotation speed of the fan and the control pivot is an open-drain or open up-collector output, which requires a pull-up to 5 V or iii.3 5 in the fan. Different linear voltage regulation, where the fan voltage is proportional to the speed, the fan is driven with a constant supply voltage; the speed command is performed by the fan based on the control signal.

The control bespeak is a square moving ridge operating at 25 kHz, with the duty cycle determining the fan speed. 25 kHz is used to raise the sound of the betoken above the range of human hearing; employ of a lower frequency could produce an audible hum or whine. Typically a fan tin can exist driven betwixt about xxx% and 100% of the rated fan speed, using a signal with upward to 100% duty cycle. The exact speed behavior at depression command levels (linear, off until a threshold value, or a minimum speed until a threshold) is manufacturer dependent.^[9]

Many motherboards feature firmware and software that regulates these fans based on processor and reckoner case temperatures.

Fan speed controllers [edit]

A fan controller with LEDs indicating fan status and potentiometers and switches to control fan speeds

Some other method, popular with PC hardware enthusiasts, is the manual fan speed controller. They tin be mounted in an expansion slot or a 5.25" or iii.5" bulldoze bay or come built into a computer's case. Using switches or knobs, fastened fans tin can have their speeds adapted past one of the above methods.

Hardware [edit]

Nigh modernistic motherboards feature hardware monitoring chips, which are capable of performing fan control,^[1] commonly through the PWM method equally described higher up. These fries can be configured through BIOS,^[10] ^:§11.1 or by using specialised software once the operating system has booted.

Processors produce varying levels of heat depending on organization load, thus it makes sense to reduce the speed of the fans during idle to decrease the noise produced past fans running full speed, until the load does goes upwards, at which indicate fan speed must be adjusted promptly to avoid overheating. Mod hardware monitor chips, in one case configured, are capable of independently running this monitoring loop without whatsoever demand for a operation BIOS or an operating arrangement. This automatic control offered past some chips may be chosen Thermal Cruise mode for maintaining a thermal envelope, every bit well equally Fan Speed Prowl style for maintaining a specific fan speed automatically.^[10] ^:§12

However, not all software is capable of accessing these advanced configuration parameters provided by some chips, and it is very common that the generic software implements only the virtually basic interfacing with the chips, namely, an explicit setting for the duty cycle for each fan control setting, subsequently performing the duty cycle adjustments itself in software, and thus requiring that both the operating system, too as this third-party software itself to continue running on the main CPU to perform the monitoring loop.^[10] ^:§11.3 This may non be a problem until the arrangement or the utility crashes, at which signal the organization may overheat due to the failure of the fans to maintain adequate cooling whilst running at reduced voltage and speed.

Software [edit]

Many companies at present provide software to command fan speeds on their motherboards under Microsoft Windows or Mac OS Ten/MacOS. Different software is used by different motherboards. There are also third-political party programs that piece of work on a variety of motherboards and permit wide customization of fan behavior depending on temperature readings from the motherboard, CPU, and GPU sensors, as well equally allowing manual control. Ii such programs are SpeedFan^[eleven] and Argus Monitor.^[12]

References [edit]

^ ^a ^b ^c Constantine A. Murenin (2007-04-17). "1. Background". Generalised Interfacing with Microprocessor System Hardware Monitors. Proceedings of 2007 IEEE International Conference on Networking, Sensing and Control, xv–17 Apr 2007. London, United Kingdom: IEEE. pp. 901–906. doi:x.1109/ICNSC.2007.372901. ISBN978-1-4244-1076-7. IEEE ICNSC 2007, pp. 901–906.
^ Barber, Antony (1992). Handbook of Noise and Vibration Control - Antony Hairdresser - Google Books. ISBN9781856170796 . Retrieved 2014-01-01 .
^ "Archived copy" (PDF). Archived from the original (PDF) on 2012-09-04. Retrieved 2015-02-26 . {{cite web}}: CS1 maint: archived copy as title (link)
^ Overspin Your Fans
^ "Get 12V, 7V or 5V for your Fans". Archived from the original on 2008-09-xviii. Retrieved 2016-09-03 .
^ "LM7808". fairchildsemi.com. Archived from the original on 2015-04-02. Retrieved 2014-08-xiii .
^ "LM317 - Single Channel LDO - Linear Regulator (LDO) - Clarification & parametrics". ti.com.
^ "Thermal Considerations for Linear Regulators". Nov 28, 2006. Archived from the original on 2015-04-02. Retrieved 2015-02-26 .
^ "iv-Wire PWM Controlled Fans Specification" (PDF). September 2005. Archived from the original (PDF) on 2011-07-26. Retrieved 2011-07-21 .
^ ^a ^b ^c Constantine A. Murenin (2010-05-21). OpenBSD Hardware Sensors — Ecology Monitoring and Fan Control (MMath thesis). University of Waterloo: UWSpace. hdl:10012/5234. Document ID: ab71498b6b1a60ff817b29d56997a418.
^ "SpeedFan - Access temperature sensor in your computer".
^ "Argus Monitor - Software to command CPU, GPU and Organisation fans using any bachelor PC temperature source".

External links [edit]

iv-Wire PWM Controlled Fans Specification v1.3, Intel
3-Wire and iv-Wire Fan Connectors, Intel
three-Wire, iv-Wire Motherboard Fan Connector Pinouts, AllPinouts
Why and How to Control (two/iii/4-wire) Fan Speed for Cooling Electronic Equipment, Analog Devices
Controlling fanspeeds in Linux on PWM motherboards, Thinkpads and ASUS Eee PC