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21 octobre 2010 4 21 /10 /octobre /2010 04:10

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 and storage devices and energy-efficient parts      (Dell XPS M1210 Battery)          .

Like noise, the term "quiet PC" is subjective and there is currently no standard definition for a "quiet PC". However, a general definition accepted by some is that the sound emitted by such PCs should not exceed 30 dBA when measured 1 meter away from the computer      (Dell Studio XPS 1340 Battery)          .

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 sound 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      (Dell Studio XPS 1640 Battery)          .

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         (Dell Vostro 1710 Battery)        .
  • As the fan blades spin, they produce a vortex of air that trails off the edge of the blade. When the vortexes 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 .     (ASUS EEE PC900 battery)

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, motor rotation speed for hard disc drive (HDD) and Optical disc drive (ODD) has been rising for faster data processing with technical advances in micro motors         (Dell RM791 battery)         .

Faster rotation (usually measured in RPM) causes higher bearing friction, thus more noise, given the same bearing technology.

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 fan noise running on high RPM. 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      (Sony VGP-BPS13 battery)              .

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         (Sony VGP-BPL9 battery)           .

Common noise reduction methods

  • Replace heat sinks with more efficient models. This often entails the use of larger copper or aluminum heat sinks which may 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        (Sony VGP-BPL11 battery)         .
  • 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 (Sony VGP-BPL15 battery)          .
  • Replace hard drives with quieter models. Hard drives can also be replaced with laptop hard drives, with solid state devices likecompact 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   (Dell Inspiron E1505 battery)   .
  • 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       (Dell Latitude E6400 battery)           .
  • 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 watercooling 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            (HP Pavilion dv6000 Battery)      .

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         (Sony Vaio VGN-FZ31S battery)      .
  • 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 EIST on Intel's CPUs          (Sony Vaio VGN-FZ31S battery)         .
  • 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          (Hp pavilion dv6000 battery)         .
  • 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          (Sony VGN-FW11S Battery)          .
  • 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 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         (Sony VGP-BPS13A/B Battery)            .
  • 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          (Toshiba Satellite P10 Battery)       .
  • Defragment the hard drives to reduce the drive heads' need to search widely for data, also improves performance. This may not be practical or even possible with some operating systems, such as Linux, UNIX or Free BSD.
  • 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 (SONY VAIO VGN-FZ210CE Battery)         .
  • 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         (Hp Pavilion dv3-1000 battery)      .

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     (Dell Precision M70 Battery)          .

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. Although even then, an average sound pressure level is only one factor in determining which components will be perceived as quieter            (Acer Aspire One battery)          .

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. The a quiet power supply is selected to be efficient when providing enough power for the computer        (Toshiba Satellite L305 Battery)             .

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          (Toshiba Satellite Pro M15 Battery)          .

Some motherboard manufacturers have got rid of 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         (Toshiba Satellite M65 battery)          .

CPUs

A large copper heatsink and high flow fan provide exceptional cooling for the cooler-running Pentium 4 Northwood.

The heat output of a CPU can vary according to its brand and model - to be exact, its 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 new Intel Core 2 perform better at lower clock speeds, and thus produce less heat        (Toshiba Satellite T4900 Battery)         .

Modern CPUs often incorporate energy saving systems, such as Cool'n'Quiet, LongHaul, and EIST. These reduce the CPU clock speed and core voltagewhen the processor is idle, thus reducing heat. The heat produced by CPUs can be further reduced by undervolting, underclocking or both        (Toshiba PA3399U-2BRS battery)        .

Most modern mainstream and value CPUs are made with a lower TDP to reduce heat, noise, and power consumption. Most of Intel's desktop Core 2 Duo processors have 65W TDPs, and AMD has newer processors with a TDP between 35W and 65W. Some processors come in special low power versions      (Toshiba Satellite A200 Battery)       .

Modern low power CPUs

Maximum TDP:

  • Athlon 64 X2: 45W, 65W, 85W
  • Intel Core and Core 2 series: 35W, 65W, 85W
  • Intel Pentium M and Celeron M (lacks SpeedStep)
  • VIA C7: 12W-20W (Fanless)
  • transmeta processors
  • Geode (processor): 5W, 25W
  • Intel Atom: 2W, 4W, 8W
  • Loongson: 1W, 5W, 7W (Fanless)     (Toshiba Satellite 1200 Battery)

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, 161 watts peak power consumption for an ATI Radeon HD 2900 XT 512. Because of space limitations, video card coolers often use small fans running at high speeds, making them noisy   (Toshiba NB100 Battery)     .

Display options for making a quiet computer include:

  • 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
  • Replace the GPU cooler with a larger heatsink and possibly a larger, slower fan            (Toshiba Satellite M300 Battery)
  • No video card - use a terminal, thin client, USB display or desktop sharing software if display required

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        (Dell INSPIRON 1525 battery)            .

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   (Dell Latitude D830 Battery)          .

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                     (Dell Studio 1735 Battery)          .

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        (Dell Latitude D620 Battery)    .

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       (SONY VAIO VGN-FZ150E Battery)          .

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 lots of space make it easier to quiet a PC, both by allowing for airflow and by accommodating large coolers    (Sony VGN-FZ31Z Battery)            .

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         (SONY VAIO VGN-FZ38M Battery)         .

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        (SONY VAIO VGN-FZ21m Battery)           .

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         (SONY VAIO VGN-FZ18m Battery)          .

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 will help to keep airflow minimally restricted and keep the interior clean        (SONY VAIO VGN-FZ11m Battery)           .

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.
  • absorbing airborne noise, such as with foam          (Dell Studio 1555 Battery)           .

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         (Dell Latitude D610 Battery)          .

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        (Dell Vostro 1500 Battery)  .

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 Silent PC Review 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)      (Dell Latitude D610 Battery)       .

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         (Toshiba Satellite M60 battery)            .

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        (SONY VAIO VGN-FZ11S Battery)     .

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

Intel has recently developed a piezoelectric fan for use in desktop PCs, which is quieter than motor fans and consumes a fraction of the power         (HP Pavilion DV7 Battery)         .

Watercooling

Main article: Watercooling

Watercooling 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     (Dell Vostro 1400 Battery)         .

Loops can be made up of any combination of these items and some aren't required such as the radiator or reservoir if alternatives 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 watercooling block and back to the reservoir         (Dell RM791 battery)        .

The radiator and fan efficiency has the greatest effect on the noise level and cooling efficiency but watercooling is currently the most effective and potentially quietest methods 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     (SONY VAIO VGN-FZ Battery)       .

Because of these risks and the use of water under pressure watercooling is a greater technical challenge to set up due to the number of components and case modification usually required.

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 they got noisy 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       (Hp 520 battery)              .

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           (HP Pavilion dv9000 battery)           .

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, no moving parts; making it theoretically more reliable and silent. There is scope for very high capacity drives; however, they are currently extremely expensive per GB and are fairly scarce      (Dell Vostro 1000 battery)           .

Compact Flash cards

A few people use Compact Flash (CF) cards for storage. Because they use IDE protocol, a simple adapter is all that is needed to connect CF cards to function as an IDE 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     (Dell XPS M2010 battery)         .

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           (Dell XPS M1530 battery)           .

Due to their small capacities they are easy to back up entirely, and often have 10 year or even lifetime warranties.

Windows minimization projects such as Winimize (Windows 98, less than 20MB) and 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 are less prone to viruses and other malware         (Dell Studio 1737 battery)              .

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          (Dell Inspiron 300M Battery)          .

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       (Dell Studio 1735 Battery)           .

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      (Dell Studio 1555 Battery)          .

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          (Dell Latitude E6400 battery)            .

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           (Sony Vaio VGN-FZ61B battery)     .

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 24x CD speed, 8x DVD speed). Some DVD drives have a feature, commonly calledRiplock, which reduces drive noise by slowing the drive during video playback         (Acer Aspire One battery)             .

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          (HP Pavilion DV4 Battery)          .

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                   (SONY VAIO VGN-FZ460E Battery)         .

LCD monitors tend to produce the least noise (whine) from 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         (Dell Vostro A90 Battery)            .

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        (Dell Vostro A860 Battery)            .

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