The PWM function allows the motherboard to run the fan precisely at its necessary speed. This guarantees the required cooling and minimizes the noise level. Even at low speeds, the operating sound of the new ARCTIC motor is barely noticeable. Due to sinus-magnetizing the new motor only creates about 5 % of the vibration from the commutation of a regular DC motor without a filter. If you want to improve the cooling efficiency of your computer you get several case fans working in parallel (since it takes ten fans to double the noise level). But what does it help if they don't work together? The PST assures that all of your fans listen to one control signal. E.g. you share the CPU Cooler's PWM signal and assure that your case fans stand down at low load and spin up whenever necessary.