Constantine Murenin, East Carolina University / De Montfort University

Power consumption of personal computers grows every year along with the computational capabilities. Recently produced microprocessors consume at times hundreds watts of power, which requires massive cooling resources. Most often than not, fans are used as a low-cost solution that provides adequate cooling in low- and medium-cost personal computers, whilst water-cooling is used in high-end systems. However, fans have several problems associated with them, such as noise when run at full speed and, once again, they themselves consume more electricity.

Processor manufacturers have come to realise that the power consumption of modern processors is a major drawback from creating high-end personal systems with acceptable power-drawn, so several power-saving technologies were deployed, such as deactivating some microprocessor units or modules whilst the processor is in the idle loop. The adoption of these features means that the fans may be turned off while the overall system activity is low, and turned to full speed when the system performs some processor-intensive task.

It is in the interest of the user to be able to control the speed at which fans are running in order to utilise the power-saving features of the processor and minimise the overall noise of the system. Practically, this may be proved extremely useful in situations where one is running an OpenBSD-based firewall or fileserver system in the home setting, where the overall processor activity of the server is going to be very minimal, whereas the noise of the system is of a major concern due to the desired 24hr operation of the server within the living room area. Desktop usage of hardware monitoring software is also of value, since the amount of processor idling time prevails in most desktop applications and minimised noise is of particular value.

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