273:
338:(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.
20:
358:
252:
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.
146:(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.
396:
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
345:
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.
263:
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
170:
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
280:
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
247:
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.
183:
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,
451:
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
409:
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
251:
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
150:
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
296:
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
231:
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
255:
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.
264:
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.
410:
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.
120:(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.
104:
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.
128:
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:
401:
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.
661:
139:
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
405:
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
236:
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.
669:
289:, 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.
848:
199:. 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,
171:
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.
365:
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"
346:
The exact speed behavior at low control levels (linear, off until a threshold value, or a minimum speed until a threshold) is manufacturer dependent.
501:
860:
832:
733:
136:
Vcc (Power) – nominally a +12 V supply, though it may be variable depending on fan type and desired fan rotation speed
369:
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.
708:
597:
500:. Proceedings of 2007 IEEE International Conference on Networking, Sensing and Control, 15–17 April 2007. London, United Kingdom:
636:
392:
Processors produce varying levels of heat depending on system load, thus it makes sense to reduce the speed of the fans during
195:
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
517:
349:
Many motherboards feature firmware and software that regulates these fans based on processor and computer case temperatures.
239:
Like other series regulators, the diode will dissipate power equal to its voltage drop times the current passing through it.
566:
85:. Heat production varies with system load, where periods of compute-intensive activity generate much more heat than the
880:
611:
544:
292:
For higher currents, discrete linear regulators are relatively simple to construct using a power transistor or
854:
844:
100:
needed forced cooling, and power supply fans also circulated cooling air through the rest of the PC with the
817:"Argus Monitor - Software to control CPU, GPU and System fans using any available PC temperature source"
361:
A fan controller with LEDs indicating fan status and potentiometers and switches to control fan speeds
875:
838:
776:
272:
740:
780:
419:
382:
335:
143:
117:
534:
406:
165:
33:
is the management of the rotational speed of an electric fan. In computers, various types of
26:
computer cases may contain multiple cooling fans. At the top of the case is a fan controller.
712:
8:
378:
259:
Another method of reducing the fan speed is by moving the 5 V wire in the classical
50:
447:
Many companies now provide software to control fan speeds on their motherboards under
691:"LM317 - Single Channel LDO - Linear Regulator (LDO) - Description & parametrics"
591:
540:
513:
448:
82:
66:
640:
784:
505:
38:
816:
276:
SMSC EMC2102 rotational-speed-based fan controller with hardware thermal shutdown
300:
As with other linear regulators, the waste heat that is produced will be roughly
260:
211:
whose output voltage is controlled by the potentiometer. It is possible to use a
573:
470:
233:
113:
23:
855:
Why and How to
Control (2/3/4-wire) Fan Speed for Cooling Electronic Equipment
509:
869:
861:
Controlling fanspeeds in Linux on PWM motherboards, Thinkpads and ASUS Eee PC
286:
228:
200:
196:
19:
41:, and different fan control mechanisms balance their cooling capacities and
97:
34:
227:
in series with the fan will reduce the voltage being output to the fan. A
495:
389:, or by using specialised software once the operating system has booted.
93:
70:
46:
381:
chips, which are capable of performing fan control, usually through the
357:
438:
434:
393:
342:
341:
The control signal is a square wave operating at 25 kHz, with the
204:
86:
788:
536:
Handbook of Noise and
Vibration Control - Antony Barber - Google Books
108:
Fans installed in a PC case can produce noise levels of up to 70
92:
Processors in most early x86-based computers, up to some of the early
802:
615:
366:
497:
Generalised
Interfacing with Microprocessor System Hardware Monitors
772:
OpenBSD Hardware
Sensors — Environmental Monitoring and Fan Control
465:
453:
426:
212:
192:
180:
151:
voltages, which directly affects the rotation speed of the blades.
109:
74:
690:
242:
385:
method as described above. These chips can be configured through
442:
430:
293:
281:
and LM7810, respectively. Adjustable versions like the popular
208:
282:
224:
42:
112:. Since fan noise increases with the fifth power of the fan
398:
386:
267:
78:
54:
53:
circuitry, which can be configured by the end-user through
770:
101:
803:"SpeedFan - Access temperature sensor in your computer"
768:
494:
Constantine A. Murenin (2007-04-17). "1. Background".
493:
45:
they generate. This is commonly accomplished by the
418:"Argus Monitor" redirects here. For the lizard, see
16:
Management of the rotational speed of a computer fan
867:
791:. Document ID: ab71498b6b1a60ff817b29d56997a418.
764:
762:
760:
69:grow more powerful so do their requirements for
709:"Thermal Considerations for Linear Regulators"
851:Motherboard Fan Connector Pinouts, AllPinouts
833:4-Wire PWM Controlled Fans Specification v1.3
757:
174:
734:"4-Wire PWM Controlled Fans Specification"
57:or other software to perform fan control.
330:
489:
487:
485:
356:
352:
271:
268:Integrated or discrete linear regulators
18:
726:
60:
868:
596:: CS1 maint: archived copy as title (
532:
133:Ground – common ground
769:Constantine A. Murenin (2010-05-21).
482:
243:Voltage modification ("volt modding")
711:. November 28, 2006. Archived from
154:
96:, did not need active ventilation.
13:
142:Control input – a
14:
892:
826:
637:"Get 12V, 7V or 5V for your Fans"
377:Most modern motherboards feature
285:also exist; when combined with a
123:
839:3-Wire and 4-Wire Fan Connectors
739:. September 2005. Archived from
539:. Elsevier Advanced Technology.
809:
795:
522:. IEEE ICNSC 2007, pp. 901–906.
452:control. Two such programs are
159:
701:
683:
654:
629:
604:
559:
526:
77:emit this electrical power as
1:
476:
37:are used to provide adequate
187:
179:A standard cooling fan is a
7:
459:
413:
372:
203:could be used along with a
10:
897:
424:
417:
163:
881:Computer hardware cooling
510:10.1109/ICNSC.2007.372901
218:
175:Linear voltage regulation
533:Barber, Antony (1992).
781:University of Waterloo
420:yellow-spotted monitor
362:
336:Pulse-width modulation
331:Pulse-width modulation
277:
144:pulse-width modulation
118:revolutions per minute
27:
360:
353:Fan speed controllers
275:
261:Molex power connector
22:
612:"Overspin Your Fans"
504:. pp. 901–906.
184:as described below.
61:Need for fan control
456:and Argus Monitor.
379:hardware monitoring
51:hardware monitoring
363:
278:
28:
666:fairchildsemi.com
519:978-1-4244-1076-7
449:Microsoft Windows
166:Bang–bang control
81:generated by all
888:
876:Ventilation fans
857:, Analog Devices
821:
820:
813:
807:
806:
799:
793:
792:
766:
755:
754:
752:
751:
745:
738:
730:
724:
723:
721:
720:
705:
699:
698:
687:
681:
680:
678:
677:
668:. Archived from
658:
652:
651:
649:
648:
639:. Archived from
633:
627:
626:
624:
623:
614:. Archived from
608:
602:
601:
595:
587:
585:
584:
578:
572:. Archived from
571:
563:
557:
556:
554:
553:
530:
524:
523:
491:
326:
155:Types of control
83:major components
896:
895:
891:
890:
889:
887:
886:
885:
866:
865:
829:
824:
815:
814:
810:
801:
800:
796:
767:
758:
749:
747:
743:
736:
732:
731:
727:
718:
716:
707:
706:
702:
689:
688:
684:
675:
673:
660:
659:
655:
646:
644:
635:
634:
630:
621:
619:
610:
609:
605:
589:
588:
582:
580:
576:
569:
567:"Archived copy"
565:
564:
560:
551:
549:
547:
531:
527:
520:
492:
483:
479:
462:
445:
423:
416:
375:
355:
333:
325:
318:
311:
301:
270:
245:
221:
190:
177:
168:
162:
157:
126:
63:
17:
12:
11:
5:
894:
884:
883:
878:
864:
863:
858:
852:
842:
836:
828:
827:External links
825:
823:
822:
819:. 9 July 2021.
808:
794:
756:
725:
700:
682:
653:
628:
603:
558:
545:
525:
518:
480:
478:
475:
474:
473:
471:PID controller
468:
461:
458:
415:
412:
374:
371:
354:
351:
332:
329:
323:
316:
309:
269:
266:
244:
241:
220:
217:
201:potentiometers
189:
186:
176:
173:
164:Main article:
161:
158:
156:
153:
148:
147:
140:
137:
134:
125:
124:Fan connectors
122:
114:rotation speed
98:Power supplies
62:
59:
15:
9:
6:
4:
3:
2:
893:
882:
879:
877:
874:
873:
871:
862:
859:
856:
853:
850:
846:
843:
840:
837:
834:
831:
830:
818:
812:
804:
798:
790:
786:
782:
778:
774:
773:
765:
763:
761:
746:on 2011-07-26
742:
735:
729:
715:on 2015-04-02
714:
710:
704:
696:
692:
686:
672:on 2015-04-02
671:
667:
663:
657:
643:on 2008-09-18
642:
638:
632:
618:on 2002-06-09
617:
613:
607:
599:
593:
579:on 2012-09-04
575:
568:
562:
548:
546:9781856170796
542:
538:
537:
529:
521:
515:
511:
507:
503:
499:
498:
490:
488:
486:
481:
472:
469:
467:
464:
463:
457:
455:
450:
444:
440:
436:
432:
428:
421:
411:
408:
403:
400:
395:
390:
388:
384:
380:
370:
368:
359:
350:
347:
344:
339:
337:
328:
322:
315:
308:
304:
298:
297:accessories.
295:
290:
288:
287:potentiometer
284:
274:
265:
262:
257:
253:
249:
240:
237:
235:
230:
229:silicon diode
226:
216:
214:
210:
206:
202:
198:
197:computer case
194:
185:
182:
172:
167:
152:
145:
141:
138:
135:
132:
131:
130:
121:
119:
115:
111:
106:
103:
99:
95:
90:
88:
84:
80:
76:
72:
68:
58:
56:
52:
48:
44:
40:
36:
35:computer fans
32:
25:
21:
811:
797:
771:
748:. Retrieved
741:the original
728:
717:. Retrieved
713:the original
703:
694:
685:
674:. Retrieved
670:the original
665:
656:
645:. Retrieved
641:the original
631:
620:. Retrieved
616:the original
606:
581:. Retrieved
574:the original
561:
550:. Retrieved
535:
528:
496:
446:
404:
391:
376:
364:
348:
340:
334:
320:
313:
306:
302:
299:
291:
279:
258:
254:
250:
246:
238:
222:
191:
178:
169:
160:Thermostatic
149:
127:
107:
91:
64:
47:motherboards
30:
29:
783:: UWSpace.
407:interfacing
116:, reducing
89:time does.
31:Fan control
870:Categories
789:10012/5234
750:2011-07-21
719:2015-02-26
676:2014-08-13
647:2016-09-03
622:2017-04-05
583:2015-02-26
552:2014-01-01
477:References
439:hw.sensors
435:lm_sensors
425:See also:
343:duty cycle
207:such as a
205:transistor
71:electrical
65:As modern
24:Full-tower
779:thesis).
367:drive bay
215:instead.
193:Resistors
188:Resistors
75:Computers
662:"LM7808"
592:cite web
466:Quiet PC
460:See also
454:SpeedFan
427:SpeedFan
414:Software
373:Hardware
213:rheostat
181:DC motor
841:, Intel
835:, Intel
73:power.
49:having
39:cooling
849:4-Wire
845:3-Wire
695:ti.com
543:
516:
443:envsys
441:, and
431:AIDA64
294:MOSFET
219:Diodes
209:MOSFET
777:MMath
744:(PDF)
737:(PDF)
577:(PDF)
570:(PDF)
283:LM317
234:power
225:diode
43:noise
598:link
541:ISBN
514:ISBN
502:IEEE
399:BIOS
394:idle
387:BIOS
94:486s
87:idle
79:heat
55:BIOS
785:hdl
506:doi
383:PWM
324:out
317:out
305:= (
102:ATX
67:PCs
872::
847:,
759:^
693:.
664:.
594:}}
590:{{
512:.
484:^
437:,
433:,
429:,
327:.
319:)
312:-
310:in
223:A
110:dB
805:.
787::
775:(
753:.
722:.
697:.
679:.
650:.
625:.
600:)
586:.
555:.
508::
422:.
321:I
314:V
307:V
303:P
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
