Building a Mini 'Quieter-than-a-Whisper' Linux PC

Do-It-Yourself Systems
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April 22, 2002 by Mike Polniak

Our first member contribution (!!!) is an article that describes the construction of a slim-line Linux PC that is "quieter than a whisper". The author built ham radios and audio equipment for a few years, then became hooked on linux after getting his first PC 2 years ago. The only negative to spending way too much time on the PC was noise -- which eventually resulted in this project.

After building a quiet, but by no means super quiet computer I still wanted to get to the point of quieter-than-a-whisper. Not wanting to go the route of water cooling or putting the computer in the basement and running the cables through the floor,the next best solution is to try for a cooler running processor, which will not require as many fans.

Background to Building a Quieter PC

I built my main computer with an AMD T-bird 1.2ghz, Abit KT7 mother board (m/b), and full size Antec SX-1030 case, including floppy, cdrom, cdrw and 2 hard drives.Along with the video card, I installed a sound card, NIC, and a TV tuner card. The system has a total of 3 fans: cpu, power supply(p/s) and case fan. The next step was to reduce the fan noise as much as possible.

The original fans were replaced with the quietest ones I could find at a reasonable price (no more than $10 each). The case fan and the p/s fan are also thermal-controlled, so they normally run at reduced rpm. Since the processor is not overclocked, I was able to wire all 3 fans for 7 volts instead of 12 volts and thus reduce the rpm and resultant noise even more, while still keeping cpu temperatures around 45C. A safe recommendation is to keep the cpu below 55-60C at full load.

This experiment in noise reduction resulted in a relatively quiet PC where the noise of the 7200 rpm hard drives was the loudest sound. That led me to use the new Seagate Barracuda IV 7200 rpm drive with fluid bearing motor for a definite reduction in hard drive noiseand then continue the quest for a quieter PC.

How quiet is Quieter-than-a-whisper?

dBA Levels for some Common Sounds:

  • Threshold of hearing 0 dBA
  • Normal breathing 10 dBA
  • Whispering at 5 feet 20 dBA
  • Standard PC 35-50 dBA
  • Normal speak 60 dBA
So the quest is for a PC that produces less than 20dBA of sound.

My interest in a smaller and quieter computer was peaked by the widely publicized Shuttle Spacewalker SV24 mini PC. Reading its reviews gave me thoughts of building a really quiet PC based on its flex ATX m/b and a Celeron or PentiumIII processor.

Checking the thermal properties of the processors, showed that while a AMD 1.2 ghz T-bird's power dissipation is 66 watts ,the Tualatin .13 micron Celeron 1.0 ghz dissipates 28 watts. The Shuttle SV24 PC flex ATX m/b has a socket 370 for Celeron/PentiumIII processors. And the newest Spacewalker PC, the SV25 is compatible with the new .13 micron Celeron/Pentium.

I liked the concept of the SV24 PC for building a 'quieter-than-a-whisper' PC, but I did not want a cube shaped case. My preference was for a slim-line case like the book-PC or something around the size and shape of the thick yellow pages phone book, which sits under my 19" Viewsonic monitor.

Mini-PC next to Antec 1030

David & Goliath? Aopen slim-PC vs. Antec 1030

Case Search

After much web searching, I was not able to find the Shuttle flex ATX m/b used in the SV24. But I did find the Shuttle MV/25 m/b which is a micro ATX size. This board is 244x200mm versus 190x180mm for the down-sized flex ATX used in the Spacewalker PC. Accounting for the slightly larger size were the 5 expansion slots: 3 PCI , plus isa and amr, compared to only 1 PCI slot on the SV24 m/b. Now both these boards come with built-in video,sound and lan.

That brings up the case size considerations. Any slim-line case is less than 4 inches high thereby requiring half-height add-on boards. This is another reason I was planning on using the built-in video,sound and lan. Now in the midst of all these hardware considerations the integrated m/b would also have to be supported under linux, because thats what was going to be used for the operating system. The Shuttle CD has drivers for the Windows o/s, but I would have to find the required linux drivers.

Again a check of web sites and mailing lists showed that the VIA Apollo PLE133T chipset on the Shuttle m/b used the Trident Blade graphics engine which is supported under XFree-4.2. Similarly the lan was a RealTek RT8100, supported by the RealTek 8139 driver under linux. And the VIA686 southbridge sound is supported with the VIA82cxxx_audio driver.

Confident that linux could eventually be up and running on this m/b using all the integrated devices, it was time to find the rest of the parts for the PC.

VIA Apollo PLE133T Chipset Key Features

  • Supports Celeron, Pentium III (including Tualatin), and VIA C3 processors
  • 66/100/133MHz FSB settings
  • Integrated graphics with up to 1600x1200 @ 85Hz refresh
  • Two DIMM slots for up to 1GB of PC100/133 SDRAM
  • Support for Advanced Communications Riser (ACR)
  • Integrated 10/100Mb BaseT Ethernet controller
  • Two UltraDMA 100/66/33 Dual-channel IDE ports
  • 4 USB ports, UHCI compliant
  • Integrated Super I/O
  • Support for LPC bus for CRT, Digital Flat Panel and TV display
  • Integrated hardware monitoring
  • Advanced power management capabilities
Finding the Right Components

With enough information to satisfy me that the Shuttle MV/25 was the board I was going to build with, I needed to find the smallest case that would hold this m/b and most importantly, decide on a cool running processor.

There are actually many book-size PC cases available, and I found some as small as 12"Wx3.7"Hx14"D, but I finally chose the AOpen slim-line case H340D with a 180 watt power supply measuring 12.76"W x 3.74"H x 15.71"D. This case size is big enough for any micro ATX motherboard not just the down-sized ones. And it will work in either horizontal or upright position.

Front view of 'naked' Aopen H340D case

Above: Front view of 'naked' Aopen H340D case.

The slim case will take a full micro ATX board (244x244mm) plus hard drive, floppy and cdrom, and has a rotatable and removeable frame to hold the drives. This feature makes it really easy to swap drives in the confined space. Now it was time to look for that cool running processor that would make the truly 'quieter-than-a-whisper' PC, a reality.

The Shuttle MV/25 supports the following Socket 370 type CPU:

  • Intel FC-PGA Pentium III with 100/133MHz FSB
  • Intel FC-PGA2* Pentium III with 100/133MHz FSB
  • Intel FC-PGA Celeron with 66/100MHz FSB
  • Intel FC-PGA2* Celeron with 100/133MHz FSB
  • VIA PPGA C3 with 100/133MHz FSB

*PGA2 is for the new Tualatin Pentium and Celeron .13 micron core which is cooler running than the previous versions.

The thermal specs show that the new Tualatin Celeron would be dissipating 28 watts of heat (vs. AMD 1.2ghz T-bird @ 66 watts). And after reading the reviews of the SV24 PC running the Celeron or PentiumIII I knew a cpu fan would still be required, in the confined space of the small slim line case. If I wanted to eliminate the cpu fan I would need a cooler running processor. And a check of VIA's web site revealed that their newest VIA C3 using the Ezra-T core is the coolest running processor on the market.

This VIA C3 uses .13 micron core and has the smallest x86 processor die size, to minimize power comsumption and heat dissipation. The processor runs so cool that it can operate without a fan. And the thermal spec shows an average power dissipation of 5.6 watts while running typical desktop apps. So I have gone from a AMD T-bird at 66 watts, to the Tualatin Celeron at 28 watts to really cool processing at 5.6 watts. And no cpu fan is needed! This is the same power dissipation as the new mobile chips.

Now its time to check the internet and see if this new VIA C3 is for real. Doing a google search turned up enough satisfied VIA C3 users on various mailing lists and also a review on the VIA C3 866 (6.5X133mhz) that convinced me that this processor was worth a try in building the quiet desktop PC. Armed by this research into flex ATX motherboards, slim-line cases and cool running processors I was ready to start building a 'quieter-than-whisper' PC. The questions remaning were: Would it do the job running desktop applications, would it be stable and cool with only one fan in the whole case, and would it run linux?



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