Case fans Modern PCs have one or more case fans, and they can add to ambient noise significantly. To combat this issue, PC Power & Cooling makes an excellent low-noise case fan. (No, I don't work for them.) Their 80mm Silencer Auxiliary fans offer an impressive 27 cubic feet per minute (CFM) volume rate. PC Power & Cooling claims these fans rotate at 1,600 rpm and only generate 20 dB(A). However, these fans don't support speed monitoring, which is a useful, but not critical, feature. The case fan I use on my personal system is the Panasonic Panaflo 80mm. The Panaflo models move air in a funnel pattern and are said to be good for spot cooling. These fans, which are available in a variety of sizes, are designed for use in various electronics applications. Like the Silencer Auxiliary fans mentioned above, the Panaflo models don't support speed monitoring, either. Directron.com case fans are also very quiet. The 80mm version is rated at 24 CFM and 21 dB(A). However, these fans tend to be pricey, which is perhaps their main drawback. Nevertheless, they are high-quality, ball-bearing case fans and make excellent replacements for noisy power-supply fans.

CPU fans and heat sinks
Processor fan and heat sink combinations are mandatory on today's CPUs. CPU fans are generally smaller and spin at higher rates than case fans. This can cause them to generate a loud and persistent noise. Just as with case fans, there are many manufacturers of low-noise CPU fan and heat sink combinations. You should select these based on the CPU form factor and the amount of heat dissipation required by a particular CPU's model and speed. The material, size, and construction method of heat sinks determine how efficiently they dissipate heat. Copper tends to be a better material for heat sinks than aluminum, yet it's more expensive. However, a more efficient heat sink may help reduce the burden on the fan to cool the CPU, thereby making things quieter.

I use ThermalTake fans, as they are high performance, quiet, and less expensive than other fans of similar quality. ThermalTake's Volcano 7, for example, is designed for Intel Socket 370 and AMD Socket A and features a variable fan-speed control. ThermalTake rates them at 26 dB at low speed and 37 dB at the highest speed--5,000 rpms. ThermalTake also makes video and chipset fans. Some other companies that make low-noise CPU fans include:

• Antec
• Zalman
• Molex
• PC Power & Cooling