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349:(PWM) is a common method of controlling computer fans. A PWM-capable fan is usually connected to a 4-pin connector (pinout: Ground, +12 V, sense, control). The sense pin is used to relay the rotation speed of the fan and the control pin is an open-drain or open-collector output, which requires a pull-up to 5 V or 3.3 V in the fan. Unlike linear voltage regulation, where the fan voltage is proportional to the speed, the fan is driven with a constant supply voltage; the speed control is performed by the fan based on the control signal.
31:
263:
24 V voltages can be achieved, 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 being required to provide a −5 V power line and the limited power delivery capability of the −12 V line (usually less than 1 A of current) reduces the total capacity for volt modded fans in modern systems.
157:(PWM) input signal, used when the cooling fan assembly has an internal motor driver circuit. Fan assemblies with this control input provide the ability to adjust the rotational speed of the fan without changing the input voltage delivered to the cooling fan assembly. A variable rotation speed allows the cooling rate to be adjusted to meet demand, quietening the fan and saving energy when full speed is not required.
369:
407:
to decrease the noise produced by fans running full speed, until the load does goes up, at which point fan speed must be adjusted promptly to avoid overheating. Modern hardware monitor chips, once configured, are capable of independently running this monitoring loop without any need for a functioning
356:
determining the fan speed. 25 kHz is used to raise the sound of the signal above the range of human hearing; use of a lower frequency could produce an audible hum or whine. Typically a fan can be driven between about 30% and 100% of the rated fan speed, using a signal with up to 100% duty cycle.
274:
in the place of the Ground wire going to the fan, thereby delivering +7 V (12 V − 5 V = 7 V) to the fan. However, this is a potentially risky method, because +5 V PSU line is intended to source current only, not sink it, so the PSU is likely to get damaged in case of load on
181:
In this style of fan control, the fan is either on or off. Temperature inside the chassis is checked, and if an outside-of-range temperature is detected, fans are set to their maximum speed. When the temperature drops below a threshold again, the fans are turned back off. This control method reduces
291:
Common voltage regulator ICs like the popular LM78xx series are sometimes used to provide variable or constant voltage to fans. When thermally bonded to the computer's chassis, one of these ICs can provide up to 1 A of current at a voltage of 6, 8, 9 or 10 V for the LM7806, LM7808, LM7809
258:
The voltage a computer cooling fan receives is defined by the difference between the voltage wire (+12 V) and the ground wire (+0 V). By connecting one or both wires to a different voltage, the voltage the fan receives will be different from the default 12 V the fan was designed for.
194:
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 means more air moved and thus a higher heat exchange rate. There are a few ways to perform this regulation,
462:
or Mac OS X/MacOS. Different software is used by different motherboards. There are also third-party programs that work on a variety of motherboards and allow wide customization of fan behavior depending on temperature readings from the motherboard, CPU, and GPU sensors, as well as allowing manual
420:
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, as well as this third-party software itself to continue running on the main CPU to
262:
Increasing the voltage over the default 12 V 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 V power line in the +12 V input of the fan connector. Through this procedure, 10, 17 and
161:
The color of the wires connected to these pins varies depending on the number of connectors, but the role of each pin is standardized and guaranteed to be the same on any system. Cooling fans equipped with either two- or three-pin connectors are usually designed to accept a wide range of input
307:
and a small signal transistor or a Zener diode as a voltage reference. While discrete regulators require additional components (a minimum of two transistors, three resistors and a small capacitor), they allow for arbitrarily high currents, allowing for the regulation of additional fans and
242:
provides a relatively constant voltage drop of about 0.7 V per diode; data sheets for a specific diode specify its voltage drop, for example the 1N4001 silicon diode's voltage drop varies from approximately 0.7 to 0.9 V as the current varies from 0.01 to 1 A. The
266:
Connecting the +5 V power line to the +12 V input of the fan reduces the voltage the fan receives to +5 V. Some fans will not work at such low voltage at all, while some other fans may run at +5 V once they have started rotating at a reasonable speed.
275:
5 V PSU line being below the load generated by 7 V fans (e.g. when PC enters idle/sleep state). Also, the components inside the computer using +5 V power might be exposed to over 5 V in case of a short circuit in the fan.
421:
perform the monitoring loop. This may not be a problem until the system or the utility crashes, at which point the system may overheat due to the failure of the fans to maintain adequate cooling whilst running at reduced voltage and speed.
131:(RPM) by a small amount potentially means a large reduction in fan noise. This must be done cautiously, as excessive reduction in speed may cause components to overheat and be damaged. If done properly, fan noise can be drastically reduced.
115:
standard. The byproduct of increased heat generation is that the fan(s) need to move increasing amounts of air and thus need to be more powerful. Since they must move more air through the same area of space, fans will become more noisy.
139:
The common cooling fans used in computers use standardized connectors with two to four pins. The first two pins are always used to deliver power to the fan motor, while the rest can be optional, depending on fan design and type:
412:
or an operating system. This automatic control offered by some chips may be called
Thermal Cruise mode for maintaining a thermal envelope, as well as Fan Speed Cruise mode for maintaining a specific fan speed automatically.
672:
150:
Sense (or tachometer) output from fan – outputs a signal that pulses twice for each revolution of the fan as a pulse train, with the signal frequency proportional to the fan speed
416:
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 most basic
247:
rating should be noted and some diodes may require cooling to operate at their rated current. The voltage drop across the diode will fall with temperature, causing the fan to speed up.
512:
680:
300:, these adjustable regulators allow the user to vary the fan speed of several fans at currents far in excess of what a standard potentiometer could handle.
859:
210:. Since the voltage drop is proportional to the current, the fan may not start. They need to be of the appropriate power rating. For variable fan control,
608:
182:
noise issues and power requirements during periods of low usage, but when the system is operating at capacity, the fan noise can become a problem again.
376:
Another method, popular with PC hardware enthusiasts, is the manual fan speed controller. They can be mounted in an expansion slot or a 5.25" or 3.5"
357:
The exact speed behavior at low control levels (linear, off until a threshold value, or a minimum speed until a threshold) is manufacturer dependent.
871:
528:
843:
744:
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Vcc (Power) – nominally a +12 V supply, though it may be variable depending on fan type and desired fan rotation speed
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or come built into a computer's case. Using switches or knobs, attached fans can have their speeds adjusted by one of the above methods.
719:
891:
555:
511:. Proceedings of 2007 IEEE International Conference on Networking, Sensing and Control, 15–17 April 2007. London, United Kingdom:
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Processors produce varying levels of heat depending on system load, thus it makes sense to reduce the speed of the fans during
206:
in series with a fan's power pin are the simplest method of reducing fan noise, but they add to the heat generated inside the
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Many motherboards feature firmware and software that regulates these fans based on processor and computer case temperatures.
250:
Like other series regulators, the diode will dissipate power equal to its voltage drop times the current passing through it.
577:
96:. Heat production varies with system load, where periods of compute-intensive activity generate much more heat than the
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622:
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For higher currents, discrete linear regulators are relatively simple to construct using a power transistor or
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needed forced cooling, and power supply fans also circulated cooling air through the rest of the PC with the
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828:"Argus Monitor - Software to control CPU, GPU and System fans using any available PC temperature source"
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A fan controller with LEDs indicating fan status and potentiometers and switches to control fan speeds
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is the management of the rotational speed of an electric fan. In computers, various types of
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computer cases may contain multiple cooling fans. At the top of the case is a fan controller.
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Another method of reducing the fan speed is by moving the 5 V wire in the classical
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Many companies now provide software to control fan speeds on their motherboards under
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702:"LM317 - Single Channel LDO - Linear Regulator (LDO) - Description & parametrics"
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239:
211:
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108:
45:
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SMSC EMC2102 rotational-speed-based fan controller with hardware thermal shutdown
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As with other linear regulators, the waste heat that is produced will be roughly
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whose output voltage is controlled by the potentiometer. It is possible to use a
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81:
57:
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Why and How to
Control (2/3/4-wire) Fan Speed for Cooling Electronic Equipment
520:
449:
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404:
353:
215:
97:
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Controlling fanspeeds in Linux on PWM motherboards, Thinkpads and ASUS Eee PC
17:
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52:, and different fan control mechanisms balance their cooling capacities and
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in series with the fan will reduce the voltage being output to the fan. A
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400:, or by using specialised software once the operating system has booted.
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chips, which are capable of performing fan control, usually through the
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The control signal is a square wave operating at 25 kHz, with the
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547:
Handbook of Noise and
Vibration Control - Antony Barber - Google Books
119:
Fans installed in a PC case can produce noise levels of up to 70
103:
Processors in most early x86-based computers, up to some of the early
813:
626:
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Generalised
Interfacing with Microprocessor System Hardware Monitors
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OpenBSD Hardware
Sensors — Environmental Monitoring and Fan Control
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voltages, which directly affects the rotation speed of the blades.
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method as described above. These chips can be configured through
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and LM7810, respectively. Adjustable versions like the popular
112:
123:. Since fan noise increases with the fifth power of the fan
64:
circuitry, which can be configured by the end-user through
781:
814:"SpeedFan - Access temperature sensor in your computer"
505:
Constantine A. Murenin (2007-04-17). "1. Background".
56:
they generate. This is commonly accomplished by the
429:"Argus Monitor" redirects here. For the lizard, see
27:
Management of the rotational speed of a computer fan
802:. Document ID: ab71498b6b1a60ff817b29d56997a418.
775:
773:
771:
80:grow more powerful so do their requirements for
720:"Thermal Considerations for Linear Regulators"
862:Motherboard Fan Connector Pinouts, AllPinouts
844:4-Wire PWM Controlled Fans Specification v1.3
8:
745:"4-Wire PWM Controlled Fans Specification"
68:or other software to perform fan control.
500:
498:
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279:Integrated or discrete linear regulators
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607:: CS1 maint: archived copy as title (
600:
144:Ground – common ground
780:Constantine A. Murenin (2010-05-21).
254:Voltage modification ("volt modding")
7:
722:. November 28, 2006. Archived from
107:, did not need active ventilation.
153:Control input – a
25:
648:"Get 12V, 7V or 5V for your Fans"
388:Most modern motherboards feature
296:also exist; when combined with a
850:3-Wire and 4-Wire Fan Connectors
750:. September 2005. Archived from
550:. Elsevier Advanced Technology.
533:. IEEE ICNSC 2007, pp. 901–906.
463:control. Two such programs are
88:emit this electrical power as
1:
48:are used to provide adequate
190:A standard cooling fan is a
214:could be used along with a
908:
435:
428:
174:
892:Computer hardware cooling
521:10.1109/ICNSC.2007.372901
186:Linear voltage regulation
544:Barber, Antony (1992).
792:University of Waterloo
431:yellow-spotted monitor
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347:Pulse-width modulation
342:Pulse-width modulation
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155:pulse-width modulation
129:revolutions per minute
38:
371:
364:Fan speed controllers
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272:Molex power connector
33:
623:"Overspin Your Fans"
515:. pp. 901–906.
195:as described below.
72:Need for fan control
467:and Argus Monitor.
390:hardware monitoring
62:hardware monitoring
374:
289:
39:
677:fairchildsemi.com
530:978-1-4244-1076-7
460:Microsoft Windows
177:Bang–bang control
92:generated by all
16:(Redirected from
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887:Ventilation fans
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794:: UWSpace.
418:interfacing
127:, reducing
100:time does.
42:Fan control
881:Categories
800:10012/5234
761:2011-07-21
730:2015-02-26
687:2014-08-13
658:2016-09-03
633:2017-04-05
594:2015-02-26
563:2014-01-01
488:References
450:hw.sensors
446:lm_sensors
436:See also:
354:duty cycle
218:such as a
216:transistor
82:electrical
76:As modern
35:Full-tower
790:thesis).
378:drive bay
226:instead.
204:Resistors
199:Resistors
86:Computers
673:"LM7808"
603:cite web
477:Quiet PC
471:See also
465:SpeedFan
438:SpeedFan
425:Software
384:Hardware
224:rheostat
192:DC motor
852:, Intel
846:, Intel
84:power.
60:having
50:cooling
860:4-Wire
856:3-Wire
706:ti.com
554:
527:
454:envsys
452:, and
442:AIDA64
305:MOSFET
230:Diodes
220:MOSFET
788:MMath
755:(PDF)
748:(PDF)
588:(PDF)
581:(PDF)
294:LM317
245:power
236:diode
54:noise
609:link
552:ISBN
525:ISBN
513:IEEE
410:BIOS
405:idle
398:BIOS
105:486s
98:idle
90:heat
66:BIOS
796:hdl
517:doi
394:PWM
335:out
328:out
316:= (
113:ATX
78:PCs
883::
858:,
770:^
704:.
675:.
605:}}
601:{{
523:.
495:^
448:,
444:,
440:,
338:.
330:)
323:-
321:in
234:A
121:dB
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798::
786:(
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708:.
690:.
661:.
636:.
611:)
597:.
566:.
519::
433:.
332:I
325:V
318:V
314:P
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
