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Is It Possible To Build A Silent PC?

PC Musician
By Daniel James

As studio computers get faster, they get noisier. Is it possible to build a machine that's not just quieter than a standard PC, but completely inaudible?

My complete 'silent PC' weighs 3kg in total, and will easily fit under your arm. There are no optical drives -- this machine is designed for use on a network.My complete 'silent PC' weighs 3kg in total, and will easily fit under your arm. There are no optical drives -- this machine is designed for use on a network.Although computers are a great deal more capable of complex audio processing tasks than they were just a few years ago, the cooling implications of all that power mean they are a great deal noisier too. In the days when computers such as the Atari ST found a place in many MIDI studio setups, acoustic noise from computers wasn't an issue, and musicians could use the same off-the-shelf computer hardware as anyone else. Now specialist music PC suppliers have to utilise expensive tweaked components and sound-damping cases to bring noise down to acceptable levels. Even the Mac, as it has shared more and more components with PCs, has lost some of its traditional advantage in this area.

When conversation turns to the relentless progress of computer technology, you will often hear 'Moore's Law' quoted. This law states that the number of transistors that can be packed into a CPU will double every year or two, and so far this seems to have held true, resulting in the exponential growth of computer performance. Gordon Moore is the co-founder of Intel, so this may be something of a self-fulfilling prophecy. Low power consumption -- and therefore cool running and quiet operation -- does not appear to have been a design priority with Pentium chips, while the equivalent AMD processors, such as the Athlon, run even hotter. The Power PC chips used in Macs are said to run cooler than the equivalent Pentiums, but they too are often fitted with fans.

PC cases are now available ready-fitted with acoustic material.The C3 processor might not be as powerful as some other chips, but it runs cool.PC cases are now available ready-fitted with acoustic material.The C3 processor might not be as powerful as some other chips, but it runs cool.A typical contemporary computer has a CPU fan, a power supply rated at 400 Watts or more which has another fan, a fan on the graphics card, perhaps a fan cooling the high-speed disk drive which has a whine all of its own, and maybe a couple more fans to blow air in to the front of the case and out of the back. This kind of computer makes so much noise that subtle judgements about sound can be impossible without turning up the monitor amplifier to potentially ear-damaging levels. It's one thing to sacrifice those 'golden ears' in a lifetime of service to rock & roll, but to waste them because of badly designed equipment would be a tragedy. Unfortunately this kind of computer is all too common, because most manufacturers don't believe that the mass market is interested in ergonomic issues.

Apple's G4 Cube, with its large passively cooled heatsink, was perhaps the closest a mainstream manufacturer has got to a silent system in recent years. It wasn't available for long, being launched in the summer of 2000 and discontinued one year later. If OS X is your software of choice, a second-hand G4 Cube might be the easiest way to achieve near silence in the control room, providing the machine in question hasn't been retro-fitted with fan-cooled parts, such as a graphics card upgrade. From the current Apple range, the new iMacs are commendably quiet, but not silent, and there have been reports of noise problems with some of the more powerful G4 tower models. Laptops are generally quieter than desktop machines, but they can still produce enough whine to distress the audiophile. They are also relatively expensive, difficult to repair or upgrade and are incompatible with any audio hardware that requires a PCI slot.

Silent Options

Some bizarre and esoteric devices have been created in the pursuit of cool and quiet chips.Some bizarre and esoteric devices have been created in the pursuit of cool and quiet chips.So what options are open to those who want to build a PC that's not just quiet but silent? Cooling a system with water or other fluids instead of air might seem like a good idea at first. After all, water-cooled cars tend to be much quieter than air-cooled Volkswagens. Unfortunately, there are two big problems with liquid cooling for computers. Firstly, the liquid itself has to be cooled somehow -- and this means either bulky radiators on the computer, or a fan-cooled unit, defeating the object of a silent system. Fan-cooled liquid systems are usually designed for high-performance computers where noise isn't an issue. The more serious disadvantages are in reliability and safety: leaky plumbing and electronics just don't mix.

Is It Possible To Build A Silent PC?It is possible to cool a Pentium 4 CPU with an elaborate copper heatsink, and a large case-mounted fan. Large fans cool more quietly than small ones, because they can run relatively slowly but still push out more air. Combined with a fanless video card and fluid-bearing hard disk, this can reduce noise significantly. However, the power requirements of a Pentium system mean that a power supply of at least 300W is usually specified, and this will invariably need a fan. Although special 'quiet' power supplies are available, and are a great improvement over the cheap units supplied by default, they are still audible in a soundproofed environment. Placing an acoustically treated PC in a damped enclosure would give acceptable results for most people, although the resulting system might not be very portable.

Fan-less Silent PC.If we want to go further and remove the power-supply fan from the system design, there are two obvious solutions. The first is to move the AC mains PSU outside the case and away from the other hot components, as laptops do. This might have the additional advantage of reducing electrical noise on recordings. The other is to reduce the overall power consumption of the system so that passive cooling of the power supply is sufficient to protect it from failure. The Athlon chip would not therefore be a good choice for the centrepiece of a truly silent system, and neither Pentium or Power PC desktop machines are generally available with passively cooled power supplies.

 How Bad Is Computer Noise? 
 There doesn't seem to be any medical evidence for direct hearing damage from computer noise, but a number of researchers have reported secondary and psychological effects. Tomas Risberg, the author of the Silent PC web site, has collected a number of theories about how low-intensity noise might affect brain performance by competing for attention with the sounds you do want to listen to. The activation of the central nervous system caused by background noise might also have long-term effects on your health. 

Alternative CPUs

The complete EPIA boards are smaller than the sleeve of a seven-inch single, if you're old enough to remember those.The complete EPIA boards are smaller than the sleeve of a seven-inch single, if you're old enough to remember those.Fortunately, there are lots of other processors available, and some of them feature both low power consumption and Intel compatibility. The Transmeta Crusoe CPU has been available for a while in certain audio products (see Cutting Edge, February 2002) but isn't usually available to individuals, only to the larger manufacturers. By contrast, the VIA C3 is on sale to the public, and is usually supplied as a complete Mini ITX board with integrated peripherals such as video and network cards. Mini ITX boards are around 17cm square, which is a bit smaller than the sleeve of a seven-inch single. A number of prototype and one-off computers have been based on these tiny boards, including several designs intended for audio use, such as the Hi-Fi PC built by VIA.

The integrated C3 boards don't cost any more than typical PC motherboards, and are available with CPUs of up to 900MHz on the EPIA M9000. Unfortunately for people who want absolute silence, the 900MHz model has a small heatsink and fan on it, which are supplied already attached. Attempting to prise off the heatsink to replace it with another of greater surface area for passive operation could result in damage to the chip, and it would certainly invalidate the warranty. Two completely fanless versions do exist, though: the EPIA 5000 and EPIA M6000, with CPUs running at 533MHz and 633MHz respectively. A case is available for these boards, the Morex Procase 2688, which features a passively cooled external 12V power supply.

The Shuttle case comes with a noisy fan-cooled PSU, but I substituted a passively cooled 12V unit.The Shuttle case comes with a noisy fan-cooled PSU, but I substituted a passively cooled 12V unit.While the EPIA on-board audio chipsets would be unlikely to satisfy the professional user, the boards include one PCI slot and external connectors for Firewire and USB devices (USB 2.0 on the M6000) offering plenty of options. However, a big drawback could be a comparative lack of processing power. A C3 is not as powerful as a Pentium III or a Power PC chip running at the same clock speed, so a C3 running at 633MHz is hardly likely to be equivalent to the current Pentium 4 running at 3GHz. Some firms are, however, supplying custom C3 systems at higher clock rates: Concipia in Germany, for example, produce an 800MHz machine, albeit with what looks like a small power supply fan. Better still, reports have been made that the C3 can be clocked as high as 1GHz with entirely passive cooling, and still be less hot than an Intel chip at the same speed with a fan.

In any case, some audio applications are not particularly processor-intensive, and a fast hard disk may be a more important factor. The Seagate Barracuda IV disk, for example, usually regarded as the quietest on the market, is also a relatively fast disk. The new Barracuda V disk is based on the Serial ATA specification, which is supposed to be good for transfers of up to 150 Megabytes per second with an appropriate controller. That is more bandwidth than any processor is likely to be able to use, and should be plenty for any audio application.

 Taming The Beast  
 This talk of silent systems designed from scratch is all very well, but what if you've already invested a lot of money in a computer? If you find that you can't tell if the noise is on the recording or coming out of the box on your desk, then there are quite a few things you can do which will help.

First, locate the computer as far away from your ears as is possible without it becoming impractical to access. You can buy extension cables for mice, keyboards and monitors quite cheaply to replace the short ones supplied with computers as standard. For longer distances, you can use a device known as a KVM (keyboard, video, mouse) switch -- but this might mean you have to go for a walk every time you need to burn a CD!

Second, you can also baffle the computer with dense boards and sound-absorbing material, or put it in a cupboard or the room next door, but take care not to block air vents, as most of today's computers do need a lot of ventilation to stay cool. A maximum/minimum digital thermometer with an external probe could be of use in determining a good location. If you're in a room with a resonant wooden floor, a couple of concrete breeze blocks under the computer can make an audible difference too.

Third, consider tweaked components if you are happy to dismantle your computer. Apart from quieter power supply units and CPU fans, there are oversized fanless heatsinks for video cards and motherboards available ('north bridge' chipsets come with fans these days). As long as your hard disk runs cool enough, there are products available which enclose the disk in acoustic material, such as the SilentDrive. Unfortunately, many contemporary disks running at 7200 or even 10000 rpm and above are just too hot to be run in any kind of close-fitting case, even with aluminium heatsink plates.

By the time you've budgeted for a damping case and special silent or quiet parts, you may find they add up to more than the value of your current computer. Hopefully, some of the specialist parts should last through several upgrades, helping make them better value. But be aware that a quiet computer is not a silent computer -- and once you get used to a quiet one, you might still find it noisy. Taking notice of the problem only seems to make it worse...

 

Building The Test System

I took a 933MHz Ezra core C3 chip and fitted it to a Shuttle motherboard and SV25 case, using an oversized fanless heatsink on the processor. The new Nehemiah core C3 chip was due to be released as the system was being built, and should perform a little better at 1GHz clock speed and above.

There's plenty of sockets here, including Firewire. Unfortunately the on-board audio was never intended for pro use.There's plenty of sockets here, including Firewire. Unfortunately the on-board audio was never intended for pro use.

The Shuttle SV25 is about one-quarter the volume of a conventional PC case, and can fit in a shoulder bag, rivalling a laptop for portability. The case is made entirely of aluminium, making it both lightweight and a good heatsink in itself. The standard Shuttle 150W PSU has a fan, as does the case, because the system was originally designed for an Intel Celeron or Pentium III chip. I removed the case fan and fitted a Morex 12V DC power board from a 2688 case in the space left by the standard PSU. I added 512MB RAM and an 80GB Barracuda IV disk to create a working system, weighing around 3kg. The total retail price for the parts was under £400, not including a monitor.

On the first power-up it would have been difficult to tell if the system was working, were it not for the green LED on the front of the case. The only component making any noise at all was the hard disk, which vibrated slightly -- more so when reads and writes were taking place. The noise was not excessive, and I judged that most people could easily ignore it. Subjectively, the noise from the system was comparable to the quiet buzz of the external power unit supplied with some mixing desks.

Some silent system builders have advocated isolating the disk from the computer chassis to get around this vibration noise, using rubber mounts or suspension systems, but this creates another problem. Today's fast disks running at 7200rpm and above generate much more heat than traditional drives. This is usually designed to be dissipated through the aluminium sides of the drive into the metalwork of the computer case. Suspend or isolate the drive with rubber and the heatsink effect is lost, causing the disk to rise above its designed operating temperature. Some drive isolation units, such as the rubber O-ring based NoVibes cage, offer a fan for 7200rpm drives -- but then we're back to adding fans again.

 Web Links 
 The Silent PC web site:
www.silent.se

G4 noise page for Apple users:
www.g4noise.com/

Quiet PC (noise reduction parts supplier):
www.quietpc.com/

Noise Control (quiet parts manufacturer):
www.noisecontrol.de/

VIA (C3 chip and EPIA board maker):
www.VIA.com.tw/en/

Shuttle (boards and cases):
www.shuttle.com/

Concipia (quiet C3 computers):
www.concipia.de/

Ultim8pc (Shuttle and VIA supplier):
www.ultim8pc.co.uk/

Hexus.net (C3 system reviews):
www.hexus.net/reviews_main.php

Mini ITX board projects:
www.mini-itx.com/

 

As for performance, the compromise forced by the use of a cool-running CPU means that special care has to be taken in the selection of software. Synthesizers created entirely in software and 'virtual studios' loaded with graphics tend to take advantage of the plentiful computing resources offered by today's fast and noisy machines, so relatively low-powered silent computers lend themselves towards no-nonsense MIDI sequencing and audio work. Rather than have the system bear the full weight of Windows XP, I installed Mandrake Linux 9.0 with the updated kernel that supports the C3 processor. (There are plenty of reviews of C3 systems running Windows available on the internet: www.hexus.net offers a look at both the 933MHz and 1GHz chips, and www.MiniITX.com has numerous examples of custom machines.) On top of this I chose the Blackbox desktop, which is minimal and extremely light on resources, and the latest development version of Audacity, the cross-platform multitrack recording software. This software was installed via Ethernet, so that a CD-ROM drive could be left out of the design, creating less load on the power supply; many current high-speed CD-ROM drives also make a lot of noise during use, which would have been incongruous in a system that was supposed to be silent. Had I been away from the network with a stand-alone machine, a CD-R/W drive would have been needed to load software and burn master discs.

Testing Time

Audacity running under Blackbox on Linux looks much like it does on Windows or Mac OS, except for the title bar.Audacity running under Blackbox on Linux looks much like it does on Windows or Mac OS, except for the title bar.Overdubbing stereo 44.1kHz tracks direct to disk used around 20 percent of the 933MHz chip's CPU power, with the system accounting for about another 5 percent usage. CPU temperature started at around 30 degrees Celsius on boot and rose to 50C under load. VIA's official maximum for the chip is 75C, with a recommended working limit of 55C to 60C. Unfortunately, since the conventional power supply with its fan had been removed, air was no longer being forced through the case -- and the machine didn't cool down after load as I had hoped. Clearly the aluminium material and the ventilation holes in the case weren't enough to dissipate the heat by themselves.

I fitted an expensive pure copper heatsink to the CPU and used Arctic Silver thermal compound between the two, which is reputed to be one of the best materials for the job. Even so, the system temperature rose to about 45C after sitting at idle for two hours, and there was no evidence that the slow but steady rise in temperature would stop. Reluctantly, I added a quieter-than-average 4000rpm fan to the rear of the case, together with a Zalman Fan Mate variable resistor. This device allows the fan speed to be reduced to the point where the noise from the fan is barely audible. Certainly, the case fan was now quieter than the buzz from the Seagate hard disk, but it did add slightly to the cumulative noise. Quiet though it is, the test system can't be called a truly silent PC.

The power supply often has the loudest fans in a PC. These replacement units are tuned for lower noise output.The power supply often has the loudest fans in a PC. These replacement units are tuned for lower noise output.There is evidence that the 800MHz C3 will run without any heatsink at all for days, but for long-term passive-cooled use the ready-made EPIA integrated boards at up to 633MHz might be a safer bet than an envelope-pushing custom machine. By contrast to the C3, a current Pentium or Athlon will crash or even burn out in seconds if the heatsink becomes detached.

The Future Of Silent Systems

If you wanted to make an absolutely silent computer, the hard disk would have to go. Anything with moving parts, especially the extremely fast ones found in disk drives, has to make at least some noise. There are non-volatile memory-based storage devices (such as Compact Flash and Smart Media) available, and their price is coming down. However, hard disks continue to offer the best storage-space-to-price ratio, currently less than £1 per Gigabyte, and high-quality multitrack audio takes up a lot of space.

One possible compromise would be to have the silent system near the user running from non-volatile memory, while the noisy storage is done elsewhere on a network, outside the control room. There are 'thin client' computers already available which only do the processing related to the display, mouse and keyboard, while the heavy work gets done as far away as the network will allow. Ethernet networks are now running at Gigabit speeds, so this 'split system' approach may be feasible for creative work in the near future. Ultimately, there will always be a trade-off between computer performance and noise. But whether you use treated conventional components or devise a more radical solution to suit your environment, there is no need to put up with the annoyance of computer noise in the studio.

Published May 2003