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Reducing Fan Noise

Fans generate noise. In an effort to ensure proper cooling, many techs put several high-speed fans into a case, making the PC sound like a jet engine. You can reduce fan noise by using manually adjustable fans, larger fans, or specialty “quiet” fans. Many motherboards enable you to control fans through software.

Manually adjustable fans have a little knob you can turn to speed up or slow down the fan (Figure 10-35). This kind of fan can reduce some of the noise, but you run the risk of slowing down the fan too much and thus letting the interior of the case heat up. A better solution is to get quieter fans.

Figure 10-35 Manual fan adjustment device

Larger fans that spin more slowly are another way to reduce noise while maintaining good airflow. Fans sizes are measured in millimeters (mm) or centimeters (cm). Traditionally, the industry used 80-mm power supply and cooling fans, but today you’ll find 100-mm, 120-mm, and even larger fans in power supplies and cases.

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NOTE When shopping for fans, remember your metric system: 80 mm = 8 cm; 120 mm = 12 cm. You’ll find fans marketed both ways.

Many companies manufacture and sell higher-end low-noise fans. The fans have better bearings than run-of-the-mill fans, so they cost a little more, but they’re definitely worth it. They market these fans as “quiet” or “silencer” or other similar adjectives. If you run into a PC that sounds like a jet, try swapping out the case fans for a low-decibel fan from Papst, Panasonic, or Cooler Master. Just check the decibel rating to decide which one to get. Lower, of course, is better.

Because the temperature inside a PC changes depending on the load put on the PC, the best solution for noise reduction combines a good set of fans with temperature sensors to speed up or slow down the fans automatically. A PC at rest uses less than half of the power of a PC running a video-intensive computer game and, therefore, makes a lot less heat. Virtually all modern systems support three fans through three 3-pin fan connectors on the motherboard. The CPU fan uses one of these connectors, and the other two are for system fans or the power supply fan.

Most CMOS setup utilities provide a little control over fans plugged into the motherboard. Figure 10-36 shows a typical CMOS setting for the fans. Note that you can’t tell the fans when to come on or off—only when to set off an alarm when they reach a certain temperature.

Figure 10-36 CMOS fan options

Software is the best way to control your fans. Some motherboards come with system-monitoring software that enables you to set the temperature at which you want the fans to come on and off. If no program came with your motherboard, and the manufacturer’s Web site doesn’t offer one for download, try the popular freeware SpeedFan utility (Figure 10-37). Written by Alfredo Milani Comparetti, SpeedFan monitors voltages, fan speeds, and temperatures in computers with hardware monitor chips. SpeedFan can even access S.M.A.R.T. information (see Chapter 11, “Hard Drive Technologies”) for hard disks that support this feature and shows hard disk temperatures, too, if supported. You can find SpeedFan at www.almico.com/speedfan.php.

Figure 10-37 SpeedFan

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CAUTION SpeedFan is a powerful tool that does far more than work with fans. Don’t tweak any settings you don’t understand!

Even if you don’t want to mess with your fans, always make a point to turn on your temperature alarms in CMOS. If the system gets too hot, an alarm will warn you. There’s no way to know if a fan dies other than to have an alarm.

When Power Supplies Die

Power supplies fail in two ways: sudden death and slowly over time. When they die suddenly, the computer will not start and the fan in the power supply will not turn. In this case, verify that electricity is getting to the power supply before you do anything. Avoid the embarrassment of trying to repair a power supply when the only problem is a bad outlet or an extension cord that