The Cultiv8 150mm square PC fan is super slim. The small size and quiet operation make it an ideal fan for use in small compact areas. A fan is a hardware device that keeps the overall computer, or a computer device cool by circulating air to or from the computer or component. The speed of a fan is measured in revolutions per minute or RPM, and the higher the RPM rating, the faster the fan spins. However, in many cases, the higher the RPM rating, the louder a fan maybe.