Under normal circumstances, the CPU in your desktop PC generates modest amounts of heat; a smart fan on top of the CPU runs just fast enough to keep it cool. At this speed, you barely hear the fan. When your computer performs intensive tasks such as playing high-definition video, the CPU heats up and the fan runs faster. The smart fan function adjusts the fan’s speed, running it faster and slower to meet the CPU’s varying demands for cooling.
Without a fan to cool it, your computer’s CPU would overheat and literally burn itself up. Normal CPU temperatures depend on the type of the chip but average from about 86 to 140 degrees Fahrenheit. Software in your computer monitors a component on the processor chip called the Digital Temperature Sensor, adjusting the smart fan’s speed to keep CPU heat under control.
Early CPUs in the 1980s ran relatively slowly and didn’t produce much heat. With the generations of processors that followed, speeds increased and temperatures rose, requiring cooling fans on the processor itself. Eventually, constant fan noise became a problem. Because the CPU’s temperature varies according to its workload, engineers solved the noise problem by creating a variable-speed smart fan that ran only as fast as circumstances required. When the computer is idle or processing small tasks, the fan is nearly inaudible. The fan runs at maximum speed only when the CPU is busy for prolonged periods.
Although the microprocessors in notebook computers have energy-efficient designs and run cooler than their desktop-bound cousins, many still produce enough heat to require a fan. A cooling fan consumes energy as any active component does, reducing the battery’s operating time. A smart fan in the notebook is usually off unless the computer is handling a heavy workload. This keeps the machine quiet as well as extending battery life.
BIOS and Software
Your computer’s BIOS contains software that manages the fan speed; for the technically proficient, the BIOS setup screen lets you change the smart fan’s settings. Other than in the BIOS, most users never see the smart fan at work. You can, however, download software programs such as SpeedFan that display the CPU temperature and fan speed in a convenient Windows utility. The software lets you monitor and change the smart fan settings without having to reboot your computer.