PC Fans: Difference between revisions

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* Intel's [https://www.intel.com/content/dam/support/us/en/documents/intel-nuc/intel-4wire-pwm-fans-specs.pdf 4-Wire Pulse Width Modulation Controlled Fans] spec, revision 1.3 (2005-09)
* Intel's [https://www.intel.com/content/dam/support/us/en/documents/intel-nuc/intel-4wire-pwm-fans-specs.pdf 4-Wire Pulse Width Modulation Controlled Fans] spec, revision 1.3 (2005-09)
* Noctua's [https://noctua.at/pub/media/wysiwyg/Noctua_PWM_specifications_white_paper.pdf PWM Specification White Paper] (unknown date, but it references 1.3 <i>ibid</i>)
* Noctua's [https://noctua.at/pub/media/wysiwyg/Noctua_PWM_specifications_white_paper.pdf PWM Specification White Paper] (unknown date, but it references 1.3 <i>ibid</i>)
Almost all available fans are either 5V, 12V, or 24V, with 12V dominating personal computers (there is no readily-available 24V source from an [[ATX]] power supply), though 5V fans are seen in conjunction with MCUs such as [[Raspberry Pi]]. Fans operating at higher voltages will require less current for the same work. Two-pin fans offer neither feedback nor PWM control. Three-pin fans typically offer a tachometer signal on the third wire. Four-pin fans add a PWM control on the fourth wire (some fans without PWM control can still be controlled via varying voltage; voltage ought be kept constant for a PWM fan). PWM is a <b>5V logical control</b> that does not modify supplied power.
Almost all available fans are either 5V, 12V, or 24V, with 12V dominating personal computers:
* there is no readily-available 24V source from an [[ATX]] power supply, but you'll see 24V in e.g. [[3D printers]]
* 5V fans are seen in conjunction with MCUs such as [[Raspberry Pi]]
Fans operating at higher voltages will require less current for the same work. Two-pin fans offer neither feedback nor PWM control. Three-pin fans typically offer a tachometer signal on the third wire. Four-pin fans add a PWM control on the fourth wire (some fans without PWM control can still be controlled via varying voltage; voltage ought be kept constant for a PWM fan). PWM is a <b>5V logical control</b> that does not modify supplied power.


Fans can be run at less than their maximum duty to reduce acoustic noise and consume less power.
Fans can be run at less than their maximum duty to reduce acoustic noise and consume less power.