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. Control input – a pulse-width modulation (PWM) input signal, used when the cooling fan assembly has an internal motor driver circuit.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.

Vcc (Power) – nominally a +12 V supply, though it may be variable depending on fan type and desired fan rotation speed.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: The common cooling fans used in computers use standardized connectors with two to four pins. If done properly fan noise can be drastically reduced. This must be done cautiously, as excessive reduction in speed may cause components to overheat and be damaged. Since fan noise increases with the fifth power of the fan rotation speed, reducing revolutions per minute (RPM) by a small amount potentially means a large reduction in fan noise. Since they must move more air through the same area of space, fans will become more noisy.įans installed in a PC case can produce noise levels of up to 70 dB. 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. Power supplies needed forced cooling, and power supply fans also circulated cooling air through the rest of the PC with the ATX standard.

Processors in most early x86-based computers, up to some of the early 486s, did not need active ventilation. Heat production varies with system load, where periods of compute-intensive activity generate much more heat than the idle time does. Computers emit this electrical power as heat generated by all major components.

3.2.4 Integrated or discrete linear regulatorsĪs modern PCs grow more powerful so do their requirements for electrical power.

3.2.3 Voltage modification ('volt modding').

Notebook fancontrol config threshold