Your Biggest Fan
The loudest part of any PC is the fans. This includes the sounds the fans themselves make while spinning, the sound of the air moving, and turbulence created by obstructions. The faster a fan spins, the more air it moves. This provides better cooling, and more noise. For quieter operation, use fans with pulse-width modulation, or PWM. Unlike the fixed-speed fans found on cheaper PCs, PWM fans dynamically adjust their speed in response PC’s temperature, spinning more slowly (and more quietly) when the system is cool. Shop for purpose-built quiet fans from brands like be quiet! and Nocturna. Look for a sound ratings below 20 dBA, which is about as loud as a calm room. The lower the dBA value, the quieter the fan. If you already have PWM fans installed, use fan control software to set a more conservative fan curve. The fan curve controls how fast your fans spins for a given sensor’s temperature. Slowing down the fans will let components get hotter, but the risk is low within standard operating temperatures. Most pre-built fan curves run your fans faster than necessary, producing needless noise. Fan control software like SpeedFan (Windows), smcFanControl (macOS), or lm-sensors (Linux) gives you direct control over your fan speed curve. Some motherboards can also control fan speed, like Asus’ Fan Xpert. Installing additional fans may also reduce noise, ironically. With more fans, each individual fan spins more slowly, producing less noise. Because sound follows a logarithmic scale, the additional fans produce minimal audible noise at low speeds.
Clear A Path
When air flows around an object, its flow becomes more turbulent. Turbulent air makes more noise. In fact, most of the sound you hear from a fan is the sound of turbulent air flowing around obstructions. To keep things quiet, make sure there’s a mostly-unobstructed path for air to follow through your machine. In most cases, you’ll want to ingest air from the front of the PC and exhaust it out the back. Depending on the configuration of your case, there might be something dense like a hard drive tray in front of your intakes. This obstruction produces turbulent air, which is much louder than smoothly flowing air. You likely can’t remove every obstruction from the front of your machine, but do your best to limit them if possible. Check for dust bunnies inside and outside your machine. If allowed to, dust will build up and clog air intakes, limiting the efficiency of your fans. This causes them to spin more rapidly, producing more noise and sucking in more dust. Dirty shop floors, pet hair, and cigarette smoke compound the problem. Clean dust from of your PC carefully, removing dust with a clean, lint-free cloth and diluted isopropyl alcohol. You can use compressed air on stubborn clumps, but take care to avoid spraying droplets of liquid on sensitive components. Never use a vacuum or cleaning solutions, or you’ll risk destroying your PC.
Shake, Rattle and Roll
Rare, loose or improperly installed components can also produce noise. Because your whole case vibrates at a low amplitude (a consequence of the spinning fans), that shaking is imparted to anything with a physical connection to the machine. Rattle has a distinctive buzzing sound, and can be constant or intermittent. Toolless drive bays are also a common source of noise, especially if they’re not firmly seated. In fact, any aging or loose component can produce noise. With your computer off, give the components a gentle wiggle to see if they have much play. You can also experiment with immobilizing a suspect component while hearing the noise. If the sound disappears, you’ve found the source. Older-style spinning hard drives (HDDs) are another noisy component. You can buy quieter HDDs, but you’ll see better noise reducing with a large-capacity SSD with no moving parts.a
Silence At Any Cost
Sound reducing foam inserts can lower audible noise from your machine, but they aren’t as effective as removing the source of the noise. They work best on high-pitched sounds, but rarely produce miracles. In rare cases, cheap power supplies emit a high-frequency whining or ringing known as “coil whine.” It’s a high-pitched, electronic buzz or squeal similar to the sound of cheap fluorescent lights. If you hear this sound, you can try to dampen it. But the best move is to replace your power supply with a higher-quality alternative. If you want an absolutely silent machine, you’ll need to remove every single moving part, including the fans. With SSDs, this is easier than ever. But if you must have silence, then you need to build your PC with that goal in mind. A fanless system needs ultra-low-power components and passive cooling, or it will overheat too quickly to be useful.
Conclusion: Best Bets
When silencing your PC, you’ll get the most mileage from reducing fan noise by replacing loud static fans with quiet PWM fans and clearing their cooling path of dust and obstructions. Beyond that, you’ll need to apply a sharp ear and a searching hand to locate the source of and undesirable sounds.
