Quiet PC

A quiet PC is a personal computer that makes little noise. Common uses for quiet PCs include video editing, sound mixing, home servers, and home theater PCs. A typical quiet PC uses quiet cooling, quiet storage devices, and energy-efficient parts.

Like noise, the term "quiet PC" is subjective and there is currently no standard definition for a "quiet PC". A proposed general definition is that the sound emitted by such PCs should not exceed 30 dB_A. In addition to the average sound pressure level, the frequency spectrum and dynamics of the sound are important in determining if the sound of the computer is noticed. Sounds with a smooth frequency spectrum (lacking audible tonal peaks), and little temporal variation are less likely to be noticed. The character and amount of other noise in the environment also affects how much sound will be noticed or masked, so a computer may be quiet with relation to a particular environment or set of users.

History

Prior to about 1975, all computers were typically large industrial/commercial machines, often in a centralized location with a dedicated room-sized cooling system. For these systems noise was not an important issue.

With the development of the home computer, early systems such as the Commodore 64 were very low wattage and were often fanless. If there was a fan, it was a low-speed fan only used to cool the power supply, such as in the IBM PC XT.

Fan noise only started to become an issue as CPU processing power increased. Processors up to about 60 megahertz did not require anything more than a single case fan and a passive heatsink. Beyond that point, a fan would be installed over the CPU heatsink to blow air straight down onto the processor, in what is known as spot-cooling. There was no regard for where the intake air came from, or where exhaust was going. The sole purpose of the fan was to move heat from a small concentrated location under the heatsink into the larger air mass inside the computer case.

As desktop computers grew in performance, more fans were included to provide spot-cooling in many more specific locations where heat dissipation was needed, without regard to overall airflow or trying to do thermal analysis of cooling efficiency.

• Originally, video display controllers were fairly low power devices without any need for active cooling. But with the development of the 3D graphics card, it became common for the video card to have its own fan, separate from a general case/system fan. The development of 3D cards working in tandem required separate spot-cooling fans for each card.
• Multiprocessor systems such as the Pentium Pro typically needed a separate spot-cooling fan for each CPU.

Computer cases often have not been designed to consider the overall airflow of the system, while spot-cooling fans only focus on cooling a specific location without regard to where the exhaust air is going. Sometimes fan airflow is not coordinated, such as with the power supply and case fans both blowing air in or sucking air out, with no other venting. This combination could lead to a system with a large number of internal spot-cooling fans that is overheating because there is poor overall airflow into and out of the case.

Green PC

With the developing social interest in energy conservation, the concept of designing systems to only consume as much power as is needed at a particular moment has helped to reduce both power consumption and system noise.

Initially this was not important for large industrial/commercial systems and for home computers, and systems typically operated at full power consumption all the time, with cooling systems also designed to operate at maximum cooling capacity all the time. The screensaver for example, is an animated motion of a computer screen designed to prevent image burn-in, used at a time when computer monitors tended to stay powered on all the time, or only turned off by operation of a physical switch.

Energy conservation first started to become an issue with the development of portable computers that had limited battery power, for which reduced power usage directly translates into a longer operating time. System noise is also a factor for laptops since the noise producing components cannot be shifted away to another location. The first low power and energy conserving CPUs were developed for use in laptops, while desktops continued to operate at fixed high power levels.

Large industrial systems such as network file servers and database servers were the last to get power conservation measures added, since their primary focus is high performance centralized operation. However, as system density and power usage increased, businesses began to recognize that server systems do not need to run at full power all the time, and there is money to be saved using a server that reduces power consumption when it is not needed. At the individual server level the cost savings are small but for a large business with hundreds to thousands of systems, the savings can be significant.

Causes of noise

The main causes of PC noise are:

• Mechanical friction noise generated by micro motors and fan bearings, as well as vibration noise from low quality chassis and improper assemblies.
• Turbulence caused by obstructions in the flow of air, such as poorly designed fan grilles and heatsinks. A lack of clearance between rotating fan blades and nearby support struts and grilles will create an audible noise, similar to how a mechanical siren operates. As the fan blades spin, they produce a vortex of air that trails off the edge of the blade. When the vortex's path crosses an object it may produce noise. Fan blades can be designed to reduce this problem by using special notched shapes.
• Noise generated by electrical coils or transformers used in power supplies, motherboards, video cards or LCD monitors.
• Other components with rotating (motors) or oscillating (voice coil) parts such as disk drives (hard, floppy, compact, DVD), tape streamers. They are also internally dampened to reduce the noise they generate and often incorporate resilient mounting points.

Noise in personal computers has been increasing with rising computing power and number of transistors on a single die (integrated circuit). More transistors of a given size use more power, which releases more heat. Faster-rotating cooling fans are one common way to remove this heat. Also, the rotation speeds of hard disk drives and optical disc drives have increased. Higher rotation rates can increase vibration and bearing friction, thus creating more noise.

The noise issue had received widespread attention with AMD's early Athlon CPUs and Intel's Pentium 4 Prescott core CPU known for its excessive heat and bundled high RPM fan noise. With the introduction of Home Theatre PCs (HTPC), the excessive heat and noise problem that had been mostly confined to the overclocking and quiet computing communities came to the attention of the general public.

The main approaches to reducing noise problems from personal computers are:

1. Reduce heat generation by using energy efficient parts - nearly all the energy used by a computer is converted into heat.
2. Improve cooling by using more efficient cooling parts and lower friction, quieter bearings.
3. Use soundproofing to reduce the effects of remaining noise sources.

Noise reduction methods

Reducing noise with new CPU cooler.

This passive heat sink in a Power Mac G4 relies on large surface areas

Common noise reduction methods

• Replace heat sinks with more efficient models. This may entail the use of larger copper or aluminum heat sinks that incorporate heat pipes.
• Replace fans with passive cooling solutions where possible, such as fans on motherboards and GPUs.
• Replace fans with low-speed, large-diameter fans with low bearing and motor noise. Larger fans can move more air per revolution than smaller fans.
• Replace the constant-speed fan in the power supply with a thermostatically controlled variable speed fan that runs at less than maximum speed, and thus runs quieter, most of the time.
• Replace the power supply with a quieter model. The main considerations, from a noise-reduction point of view, in choosing a power supply are fan quality, AC/DC conversion efficiency, and how good the thermal fan speed control is at keeping the fan running slow and steady. Efficiency is important because the less heat that is produced the less work the fan has to perform.
• Replace hard drives with quieter models. Hard drives can also be replaced with laptop hard drives, with solid state devices like compact flash or networked file systems like NFS. This reduces or eliminates this source of noise and reduces system power and cooling requirements.
• Place a damping material around hard drives (or other spinning drives) such as Sorbothane
• Cover the case with sound insulation material such as rubber, foam or fiber mat, although this method has limited effectiveness. The material can (because of its weight) dampen case resonance, and can also absorb some high-frequency sound. Care must be taken to be sure the soundproofing does not interfere with airflow and cooling.
• In energy-hungry computers, water cooling may be necessary for quiet operation. Older water pumps sometimes can make systems noisier than air-cooled, low-power computers. However, recent advances in 12V DC pump technologies have resulted in highly reduced noise levels from many pumps. In a modern water-cooling system geared towards silence rather than performance, the loudest component in the computer is often the hard drive or optical disc drive when performing accesses to the media.

Low-cost methods

A number of methods exist for reducing computer noise at little or no added cost.

• Reduce CPU supply voltage ("undervolting"). Many of today's CPUs can run stably at their stock speed, or even with a slight overclock, at a reduced voltage, which reduces heat output. Underclocking can be done for the same effect, however this reduces performance and is not as effective as undervolting; all the same, underclocking may allow further undervolting. Power consumption is approximately proportional to V²·f, that is, it varies linearly with the clock frequency and quadratically with the voltage. This means that even a small reduction in voltage can have a large effect in power consumption. Undervolting and underclocking can also be used with chipsets and GPUs.
• Enable Cool'n'Quiet for AMD CPUs or SpeedStep (also known as EIST) on Intel's CPUs.
• Reduce fan speed. For newer computers, the speed of fans can be varied automatically, depending on how hot certain parts of the computer get. Lowering a DC fan motor's supply voltage will reduce its speed while making it quieter and lowering the amount of air the fan moves. Doing this arbitrarily could lead to components overheating; therefore, whenever performing hardware work it is advised to monitor the temperature of system components. Fans with Molex connectors can be modified easily. With 3-pin fans, either fixed inline resistors or diodes, or commercial fan controllers, such as the Zalman Fanmate, can be used. Software like speedfan may allow fan speed control. Many newer motherboards support pulse-width modulation (PWM) control, allowing the fan speed to be set in the BIOS or with software.
• Mount fans on anti-vibration mounts.
• Remove restrictive fan grills to allow easier airflow, or replace noisy fan grills with quieter versions.
• Use software such as Nero DriveSpeed or RimhillEx to reduce the speed of optical drives.
• Isolate hard disk noise, either by using anti-vibration mounts (generally rubber or silicone grommets), or by suspending the hard disk to fully decouple it from the computer chassis by mounting it in a 5.25 inch drive bay with viscoelastic polymer mounts.
• Set the hard disk's AAM value to its lowest setting. This reduces the seek noise produced by the hard drive, but also reduces performance slightly.
• Set operating system to spin down hard drives after a short time of inactivity. This may reduce a drive's life span and commonly conflicts with the OS and running programs, though it can still be useful for drives that are only used for data storage.
• Defragment hard drives to reduce the drive heads' need to search widely for data. This can also improve performance.
• Arrange components and cables to improve airflow. Wires hanging inside the computer can block the airflow, which can increase the temperature. They can be easily moved to the side of the case so that air can pass through more easily
• Remove dust from inside the computer. Dust on computer parts will retain more heat. Fans draw in dust along with outside air, it can build up quickly inside the computer. Dust can be removed with a vacuum cleaner, gas duster or compressed air. Special anti-static vacuum cleaners should be used however to prevent electrostatic discharge (ESD). Ideally, this would be done often enough to prevent a significant amount of dust from ever building up. How frequently this would need to be performed would depend entirely on the environment in which the computer is used.
• Relocate computer outside working or living room, using long-distance HDMI/USB/DVI cables: those available in 5/10/15 m length. That is enough to relocate PC into next room, using through hole in the wall for the cables. Supplemental (nonresidential) room could have optional noise isolation. Digital cables do not lose data/quality of signal. Display, monitor, printer, scanner, etc., power supplies should be relocated to the supplemental room as well, because any voltage transformer produce some noise. DVD/BD drive (as any peripheral device) could be connected separately, using USB cable. Power management, like waking up from sleep mode might be performed remotely, using special types of USB keyboards. Thin clients and terminal services can also be used, like accessing a high-performance machine, possibly virtualised, using a Raspberry Pi (a miniature computer that does not even use a heat sink) over a SSH/VNC connection.

Sound power and pressure measurement

Though standards do exist for measuring and reporting sound power output by such things as computer components, they are often ignored. Many manufacturers do not give sound power measurements. Some report sound pressure measurements, but those that do often do not specify how sound pressure measurements were taken. Even such basic information as measurement distance is rarely reported. Without knowing how it was measured, it is not possible to verify these claims, and comparisons between such measurements (e.g. for product selection) are meaningless. Comparative reviews, which test several devices under the same conditions, are more useful, but even then, an average sound pressure level is only one factor in determining which components will be perceived as quieter.

Individual components in a quiet PC

The following are notes regarding individual components in quiet PCs.

The motherboard, CPU, and video card are major energy users in a computer. Components that need less power will be easier to cool quietly. A quiet power supply is selected to be efficient while providing enough power for the computer.

Motherboards

Main article: Motherboards

Passively cooled northbridge chipsets help reduce noise.

A motherboard based on a chipset that uses less energy may be easier to cool quietly.

Many modern motherboard chipsets have hot northbridges (notably nForce4), which may come with active cooling, usually a small, noisy fan. Fanless heatsinks, such as the Zalman ZM-NB47J, ZM-NBF47 or the Thermalright HR-05, may be used to eliminate a noisy chipset fan. Some motherboard manufacturers have replaced these fans by incorporating large heatsinks or heatpipe coolers, however they still require good case airflow to remove heat. Also, motherboard voltage regulators often have heatsinks and may need airflow to ensure adequate cooling.

Motherboards can also produce coil noise.

Undervolting and underclocking generally require motherboard support.

Some motherboards can control the fan speed using software like SpeedFan. Most recent motherboards have built in PWM based fan control for one or two fans.

CPUs

The heat output of a CPU can vary according to its brand and model or, more precisely, its thermal design power (TDP). Intel's third revision Pentium 4, using the "Prescott" core, was infamous for being one of the hottest-running CPUs on the market. By comparison, AMD's Athlon series and the Intel Core 2 perform better at lower clock speeds, and thus produce less heat.

Modern CPUs often incorporate energy saving systems, such as Cool'n'Quiet, LongHaul, and SpeedStep. These reduce the CPU clock speed and core voltage when the processor is idle, thus reducing heat. The heat produced by CPUs can be further reduced by undervolting, underclocking or both.

Most modern mainstream and value CPUs are made with a lower TDP to reduce heat, noise, and power consumption. Intel's dual-core Celeron, Pentium, and i3 CPUs generally have a TDP of 35–54 W, while the i5 and i7 are generally 64–84 W (in the newest variant, Haswell) or 95W (older versions, such as Sandy Bridge). Older CPUs such as the Core 2 Duo typically had a TDP of 65 W, while the Core 2 Quad CPUs were mostly 65–95 W. AMD's Athlon II x2 CPUs were 65 W, while the Athlon x4 was 95 W. The AMD Phenom ranged from 80 W in the x2 variant to 95 and 125 W in the quad-core variants. The AMD Bulldozer CPUs range from 95–125 W. The APUs range from 65 W for the lower-end dual-core variants, such as the A4, to 100 W in the higher-end quad-core variants, such as the A8. Some processors come in special low power versions. For example, Intel's lower TDP CPUs end in T (35 W) or S (65 W).

Modern low-power CPUs

Maximum TDP:

• AMD Fusion C and E-series: 9–18 W
• Athlon 64 X2: 45, 65 or 85 W
• Intel Core and Core 2 series: 35, 65 or 85 W
• Intel Pentium M and Celeron M (lacks SpeedStep)
• Intel Xeon L55xx and L56xx series: 60 W
• Intel Celeron, Intel Pentium, i3: Normally 54 W, and 35 W in the "T" variants.
• Intel Core i5 and Intel Core i7 in the "S" variants (55 W) or T variants (35 W).
• VIA C7: 12–20 W (fanless)
• Transmeta processors
• Geode: 5 or 25 W
• Intel Atom: 1–15 W
• Loongson: 1, 5 or 7 W (fanless)

Video cards

Video cards can produce a significant amount of heat. A fast GPU may be the largest power consumer in a computer. For instance, the peak power consumption for an ATI Radeon HD 2900 XT 512 is 161 watts. Because of space limitations, video card coolers often use small fans running at high speeds, making them noisy.

Display options for making a quiet computer include:

• Replace the stock cooler of your video card with an aftermarket cooler to lower the noise with better cooling efficiency and at the same time, enhance the cooling performance. For example, the Arctic Accelero Hybrid 7970 is reviewed and tested to be an effective solution to make a quiet system.
• Use motherboard video output – typically motherboard video takes less power than an external video card, typically at the price of lower gaming or HD video decoding performance;
• Select a video card that does not use a fan:
  • many of the more efficient GPUs are available in fanless models;
  • many older video cards used less power than more recent video cards, thus heatsinks or fans were often not required;
  • use a terminal, thin client or USB display.
• Replace the GPU cooler with a larger heatsink and possibly a larger, slower fan.

Power supplies

Main article: Computer power supply

PSUs are made quieter through the use of higher efficiency (which reduces waste heat and need for airflow), quieter fans, more intelligent fan controllers (ones for which the correlation between temperature and fan speed is more complex than linear), more effective heatsinks and through designs which allow air to flow through with less resistance.

For a given power supply size, more efficient supplies, such as those certified 80 plus, generate less heat.

Selecting a power supply of appropriate wattage for the computer is important for high efficiency and minimizing heat. Power supplies are typically less efficient when lightly or heavily loaded. High wattage power supplies will typically be less efficient when lightly loaded, for instance when the computer is idle or sleeping. Most desktop computers spend most of their time lightly loaded. For example, most desktop PCs draw less than 250 watts at full load, and 200 watts or less is more typical.

Power supplies with thermally controlled fans can be made quieter by providing a cooler and/or less obstructed source of air. For instance, the power supply is in a separate compartment in the Antec P180 to keep the air supplied to the PSU cool.

The fan in a power supply can be replaced with a quieter one, although there is a risk of electric shock when doing this, and it usually voids the warranty.

Fanless power supplies are available.

• Some of them are equipped with large passive heat sinks and rely on convection or case airflow to dissipate heat. It is also imperative that such fanless power supplies be installed in a case with good ventilation.
• There are also fanless DC to DC power supplies that operate like those in laptops, using an external power brick to supply DC power, which is then converted to appropriate voltages and regulated for use by the computer. These power supplies usually have lower wattage ratings.

The electrical coils in power supplies can produce noise which can become noticeable in a quiet PC.

Cases

Main article: Computer case

Antec P180, with isolated chambers for more segregated airflow.

Another example of the Antec P180, this one demonstrating the use of the Scythe Ninja, a fanless CPU cooler.

Cases designed for low noise usually include reasonably quiet fans, and often come with a relatively quiet power supply. Some cases for quiet computers incorporate heatsinks to cool components passively.

Cases that provide more space make it easier to quiet a PC, both by allowing for airflow and by accommodating large coolers.

Case airflow

Noise optimized cases like the Antec P180 and Antec P150 often have ducting and partitioning within the case to optimize airflow and thermally isolate components. For example, the P180 has the PSU mounted in the bottom of the case in an isolated partition. This design feature allows cooler air to enter the PSU, reducing the necessary airflow and accordingly, the noise output of the fan. Apple has also employed this tactic in their G5 workstations in an effort to reduce noise. Antec's Sonata is often considered by the mainstream to be one of the quietest PC cases; however, it has since been surpassed by the P180 and other more-advanced cases. Vents and ducts may easily be added to regular cases.

More obstructive fan grills increase pressure drop and lower airflow, necessitating higher fan speeds and more noise output. They also increase the turbulence of the flow, which causes some noise of its own. Cases designed to be quiet typically have wire grills or honeycombed fan grills, which perform almost as well as wire grills; both are far superior to the old style of stamped grill.

Features that facilitate neat cable management, such as brackets and space to run cables behind motherboard tray, help increase cooling efficiency.

Air filtering

Air filters can help to prevent dust from coating heatsinks and surfaces, thereby impeding heat transfer, making fans spin faster. However the filter itself can increase noise if it restricts airflow too much, or is not cleaned, requiring a larger or faster fan to handle the pressure drop behind the filter.

Regular cleaning of air intake filters helps to keep airflow minimally restricted and the interior clean.

In some cases a fine mesh intake screen is sufficient to stop most large dust particles from entering the system. These screens should be vacuumed or washed to remove dust.

Case soundproofing

The inside of a case can be lined with dampening materials to reduce noise by:

• attenuating the vibration of the case panels via extensional damping or constrained-layer damping;
• reducing the amplitude of the vibration of the case panels by increasing their mass; and
• absorbing airborne noise, such as with foam.

Cooling systems

Main article: Computer cooling

Heat sinks

Main article: Heat sink

Heat sinks that operate efficiently with little airflow are often used in quiet computers. Typically they are (relatively) large, and have larger spaces to allow freer airflow. Often heat pipes are used to help distribute heat. For instance, in 2007, the Scythe Ninja or the Thermalright Ultra-120 were frequently used as CPU heat sinks in quiet computers.

Fans

Main article: Computer fan

A 120 mm variable speed fan.

Bearing and motor noise vary between different fan models and often between different samples of the same model.

Quiet PCs typically use larger (e.g. 120 mm) low-speed fans. Although 140 mm fans are made by some manufacturers, such as Aerocool and Yate Loon, there are very few cases or heatsinks that can use them. Fan adapters, which allow larger fans to be used in place of smaller ones, and fan brackets, like the Zalman FB123, often help when replacing small fans.

Quiet fan manufacturers include Nexus, EBM-Papst, Yate Loon and Scythe. In situations where the resistance to flow is very low, like in free-air conditions, Noctua fans also perform very well. Extensive comparative surveys have been posted by SPCR and MadShrimps.

Fan controllers can be used to slow down fans and to precisely choose fan speed. Fan controllers can produce a fixed fan speed using an inline resistor or diode, or a variable speed using a potentiometer or Pulse Width Modulation (PWM). Resistor-based fan control feeds the fan a lower voltage, while PWM fan control rapidly cycles between feeding the fan full voltage and no voltage. PWM fan control reduces rotational speed, and is the easiest and most efficient option for motherboards which have PWM fan headers. This is because PWM fans in conjunction with the motherboard chipset obtain temperature data from Digital Temperature Sensors on the CPU itself. All PWM fans are four pin, and if plugged into a conventional three pin supply will operate at full speed just like a three pin fan.

Fans can also be plugged into the power supply's 5 volt line instead of the 12 volt line (or between the two for a potential difference of 7 volts, although this cripples the fan's speed sensing) to run them at a reduced speed. Most fans will run at 5 volts once they are spinning, but may not start reliably at less than 7 V. Some simple fan controllers will only vary the fans' supply voltage between 8 V and 12 V to avoid this problem entirely. Some fan controllers start the fan at 12 V, then drop the voltage after a few seconds.

Soft mounting fans (e.g. with rubber or silicone fan isolators) can help reduce transfer of fan vibrations to other components.

An early type of piezoelectric fan the MaxChill, was sold to complement early Apple Macintosh computer memory upgrades in the 1980s. Intel, Murata and others have recently done further developments on use of piezoelectric fans in desktop PCs, these are often quieter than rotating fans and may consume less power.

Watercooling

Main article: Watercooling

Water-cooling is a method of heat-dissipation by transferring the heat through a conductive material which is in contact with a liquid, most often demineralised water and an additive to prevent bacterial growth and provide cosmetic effects. This heated water travels in a loop which usually contains a reservoir, radiator and pump. Recent advances in 12v DC pump technologies (for the first time specifically geared-for PC development) allow for new pumps to be both extremely powerful and extremely quiet. Loops can be made up of any combination of these items and some aren't required such as the radiator or reservoir if alternative methods are used. The radiator often uses one or more fans to air cool the radiator fins and dissipate the majority of the heat at this point.

The most common loop order is reservoir to pump, radiator then the water-cooling block and back to the reservoir. The radiator and fan efficiency has the greatest effect on the noise level and cooling efficiency but water-cooling is currently the most effective and potentially quietest method of cooling above ambient temperatures.

There is an inherent danger in the use of water around electrical equipment and leak testing the loop is always recommended before attaching any parts to the motherboard, after all loop connections have been made. The 12v DC pump can be run using batteries or a power supply making sure no power is going to any other part of the system. Because of these risks and the use of water under pressure water-cooling is a greater technical challenge to set up due to the number of components and case modification usually required.

Special precaution must be taken when water-cooling. It is a possibility to create condensation when a water-cooled heatsink becomes below ambient temps. This may, in fact, create the risk of frying a motherboard, videocard, hard-drive or other water-cooled components of a computer system. To veer away from said risks, correctly insulate and be mindful while making any changes to your system. This message is geared for more extreme overclockers. Yet, all modifications in water-cooling run the risk of creating condensation.

Secondary storage

Hard drives

Main article: Hard drives

Silicone grommets in a computer case for mounting a hard drive to reduce vibration.

Previously, hard drives used ball bearing motors, but these generated excessive noise when the rotational speed of the drive was increased to 5400 RPM or 7200 RPM. More recent desktop hard drives use fluid bearing motors. The first hard drive widely reputed to be quiet was the Seagate Barracuda ATA IV.

The smaller 2.5" form-factor hard drives generally vibrate less, are quieter, and use less power than the traditional 3.5" drives. On the other hand, they often have lower performance and less capacity, and cost more per gigabyte.

To minimize vibrations from a hard drive being transferred to, and amplified by, the case, hard drives can be mounted with soft rubber studs, suspended with elastics or placed on soft foam or Sorbothane. Hard disk enclosures can also help reduce drive noise. Care must be taken to ensure that the drive gets adequate cooling. Hard disk temperatures can often be monitored by SMART software.

Solid-state storage

Flash memory

Solid-state drive

Solid-state drive (SSD) storage offers faster seek times, lower power consumption, and no moving parts, making it more reliable and silent.

Compact Flash cards

Compact Flash (CF) cards may also be permanently used as secondary storage. Because they use a slightly modified Parallel ATA (PATA) interface, a simple adapter is all that is needed to connect CF cards to function as an PATA or PC Card hard disk. CF cards are also small, allowing SFF PCs to be made, produce no noise, use very little power (further reducing heat output in the AC/DC conversion in the PSU), and an insignificant amount of heat. However, they are very expensive per GB and are only available in small capacities.

There are also issues regarding the maximum number of writes to each sector; often specified as 100,000 write cycles. However, there are industrial grade cards which specify a higher number of erase cycles, and different file systems, or technologies such as Enhanced Write Filter can reduce the writes to the card. Also, CF cards will fail gradually, so it will be easy to notice before any significant amount of data are lost, unlike the possible immediate failure of HDDs. Due to their small capacities they are easy to back up entirely, and often have 10 year or even lifetime warranties.

Linux projects such as Puppy Linux mean that running an OS in small capacity, cheap compact flash card is possible. Because they have many OS components removed, they offer a smaller attack surface for malware to target.

The sustained transfer rate of current CF cards is a maximum of around 25 MB/s, compared to an average of around 70 MB/s for modern hard drives. However, the speed of flash memory is increasing at a faster rate than that of hard drives, and they have minimal seek times compared to hard drives, which increases the speed of loading many small files, and makes the PC seem more responsive as most operations performed by the OS include small files. Due to the fast seek times CF cards also don't show the effects of file system fragmentation like hard drives do.

Newer CF cards support faster transfer protocols like DMA. It is possible to use a Compact Flash card for storing only information that isn't changed very often, such as music, videos and binary executables, while storing the small configuration files and other frequently modified data on a small hard drive or i-RAM.

USB flash drives

Main article: USB flash drives

Where a motherboard supports booting from USB drives, they can be used in a similar fashion to CF cards to run the OS. With some Linux distributions, it is not much harder than using a CF card. As they both use flash memory, they have the same advantages and disadvantages, however speed is limited by the USB bus.

Gigabyte i-RAM

The i-RAM is a solid-state disk which has four DIMM slots to allow regular PC RAM to be used like a disk. It is much faster than a hard disk, does not have the write cycle limitations of flash memory, however it requires power continuously in order to maintain its contents (from standby power or a battery when the system is off), uses more power than many laptop hard drives, has maximum capacity of 4 GiB, and is expensive.

Problems and solutions

All forms of affordable solid-state storage offer relatively small capacity. They can be used as main storage for tasks which do not use large amounts of data or large programs, such as web browsing or word processing. Larger files and programs can be stored on a secondary hard drive which is only accessed when needed. Keeping the OS, often accessed files, and smaller programs on a solid-state drive means that the hard drives can be powered down much of the time. Network-attached storage, or NAS, is another alternative, allowing loud hard drives to be stored remotely.

Small USB drives or CF cards can be used to make the process of network booting easier also.

Optical drives

Optical drives can be slowed down by software to quiet them, such as Nero DriveSpeed, or emulated by virtual drive programs such as Daemon Tools to eliminate their noise entirely. Notebook optical drives can be used, which tend to be quieter, however this may be because they tend to run slower (typically 24× CD speed, 8× DVD speed). Some DVD drives have a feature, commonly called Riplock, which reduces drive noise by slowing the drive during video playback. For playback operations only 1x (or real time) speed is required.

External components

Laptops

Main article: Laptops

Laptop computers typically do not have power supply fans or video card fans, and they use smaller hard drives. They also use many lower power components. However, laptop CPU coolers are usually smaller, so may be noisier than their desktop counterparts. Limited space, limited access and proprietary components make silencing laptops more difficult.

A few laptops do not use cooling fans, for instance the Dell Latitude X1, Panasonic Toughbook W5 and T5, Fujitsu Lifebook P7120. Also, some netbooks, such as the Dell Mini 9, 10 and 12 do not have fans. The Mini 9 used SSD rather than a hard disk. The OLPC XO-1 has no internal moving parts.

Monitors

Main article: Computer display

CRT monitors can produce coil noise, as can the external power supply for an LCD monitor or the voltage converter for the monitor's backlight. LCD monitors tend to produce the least noise (whine) when at full brightness. Reducing brightness using the video card does not introduce whine, but may reduce color accuracy. An LCD monitor with an external power supply tucked out of the way will produce less noticeable noise than one with the power supply built into the screen housing.

Printers

Main article: Computer printer

Dot matrix and daisy wheel printers are often noisy, and soundproofed boxes or cabinets can be used to reduce the noise. Another solution is to locate the printer away from the immediate work area or in another room, especially if it can be controlled through a local area network.

External links

• How To Silence A Computer, US: Quiet PC .
• Build A Quiet PC, End PC noise .
• Cooling The Silent PC, End PC noise .
• Silent PC Review  – articles on various aspects of PC acoustics.
  • What is a "Silent" Computer?, Silent PC Review .
  • What is a "Silent" Computer? (in Dutch), Vrad .
  • Reference/Recommended, Silent PC Review .
  • In a nutshell, Silent PC Review .
• PC, SE: Silent .
• Parekh, Alan, Homebuilding of a PWM Fan controller (project) .