Ultra-quiet power supplies with Papst and Verax fans featuring output from between 300 and 460 Watts are available from a variety of suppliers. Popular models are Enermax and Chieftec power supplies modified with Papst fans. Power supplies with Verax fans based on Fortron Source and Seventeam devices are also available. Computer retail stores stock silent power supplies fitted with fans by other manufacturers. PC Cooling, for instance, has a TSP power supply with AX fans. With its "Be-Quiet" power supply series, Lista offers temperature-regulated fans in the low speed segment from 1000 to 1200 RPM. Prices range from $70 to $150, depending on the manufacturer, supplier and performance. Just be prepared to spend more if you want a high quality power supply with quiet operation.

Silent Power Supplies

Engelking Elektronik was one of the first manufacturers to present a passively cooled power supply. The Engelking AP2-6300SFC-A offers overall output of 300 Watts. Cooling ribs on the backside ensure that the power supply is adequately cooled, up to an operating temperature of 45°C. Should the temperature exceed this critical value, this power supply features a fan that engages if it determines there may be a danger of overheating. The Pro Silence PCS-350 by Silentmaxx gets by entirely without a fan. This power supply, with overall output of 350 Watts, is based on the same system as the Engelking model: its internal aluminum heat sink outwardly directs the heat to the back, heat-radiating cooling ribs.

Passive cooling is also available in the high-end class of power supplies over 400 Watts. Silentmaxx has announced that its passively cooled power supply with 400 Watts overall performance will be available this month. It will be equipped with a fan for emergencies, however, similar to the Engelking power supply.