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Langa Letter: Cool and Quiet, Part IILanga Letter: Cool and Quiet, Part II

<b>Fred Langa</B> continues his exploration of the causes--and cures--of noisy PCs. His solutions include some measures that you may consider counterintuitive but he proves why they'll work with your PC.

Fred Langa

March 3, 2004

3 Min Read

A Pause To Catch Our Breath
We're not quite done, but let's pause to recap the considerable ground we've covered so far in parts one and two of this series.

Most ongoing (nontransient) PC noise usually comes from the cooling fans.

There are three main components to fan noise: air turbulence (a "whoosh"); tip noise (a whir or whine); and mechanical noise (clicks, grinds, rattles, etc.).

The simplest way to reduce all fan noise is to reduce fan speed.

Reducing fan speed also reduces air flow, which reduces cooling ability, a potential danger.

You should monitor your PC's internal temperatures using a tool like the free MBM5 before, during, and after any changes to your PC's cooling system.

To maintain a safe and effective level of cooling with lower fan speeds, you'll need to do one or more of the following: increase the size of the fans; increase the number of fans; increase the size of heat sinks.

It's counterintuitive, but increasing the number of fans in your system may reduce the total system noise: Replacing, say, a 30dB factory-installed fan with two 20dB fans will cut the noise by 7dB, but can still produce the same or greater air flow.

You easily can attain truly "whisper quiet" operation (around 30dB or less) for all your PC's fans combined, using standard, inexpensive, off-the-shelf fans and components.

The simplest way to reduce a PC fan's speed is by reducing its voltage from the usual 12v to 5v. This can be done by directly connecting the fan to the PC's 5v power supply, or by stopping down the normal 12v via a resistor. And again, ready-made parts for this are easily available, and very inexpensive. In the next and last article in this series, we'll wrap it all up: I'll show you exactly how I modified my system in five successful ways--and in one unsuccessful way. I'll also show you my final results both for sound and for temperature, even after running the system through a worst-case thermal stress test. When we're done, you'll be fully armed with the information and examples you need to inexpensively and easily make your PC cooler--and quieter! Additional Resources
Noise In Computing

ISO 9296: PC Noise Standards

Understanding Noise Ratings

Acoustics Glossary

Sound Properties and Perception

Interference beats and Tartini tones

Combining Decibel Quantities Vendors

End PC Noise


Quiet Fans

Quiet PCs

Silent (ultra-quiet) PCs Now, please join in the discussion in the Listening Post. What tools do you use to keep track of what's going on inside your PC? What fans, heat sinks, or other devices have you used to keep your PC cool--and quiet? Join in! To discuss this column with other readers, please visit Fred Langa's forum on the Listening Post. To find out more about Fred Langa, please visit his page on the Listening Post.

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