Quiet PC
From Wikipedia, the free encyclopedia
A quiet PC is a personal computer that makes little noise. Common uses for quiet PCs include video editing, sound mixing, and as home theater PCs. A typical quiet PC uses quiet fans and hard drives and energy-efficient parts.
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[edit] Causes of PC noise
Cooling fans and hard drives make the most noise in computers. Fans are often found in the power supply, the CPU, the graphics card, the motherboard, and the case itself. Because hotter components need more air moved over them for cooling, noise production is positively related to thermal output. Heat itself is positively related to the computer's power consumption. Thus energy efficient parts and quiet fans are preferable for a quiet PC. Hard drive noise and heat is a function of rotational speed and the technology used in the device.
[edit] Silencing methods
Common silencing methods include:
- Replacing fans with low-speed, large-diameter fans with low bearing and motor noise. Larger fans can move more air per revolution than smaller fans.
- Replacing the power supply with a quieter model. The two main considerations in choosing a power supply are fan quality and AC-DC conversion efficiency. Efficiency is important because the less heat is produced, the less work the fan has to perform.
- Replacing heat sinks with more efficient models. This often entails the use of larger copper or aluminum heat sinks which may incorporate heat pipes.
- Replacing hard drives with quieter models.
- Replacing fans with passive cooling solutions where possible, such as fans on motherboards and GPUs.
- Covering the case with sound insulation material such as 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. It can also have the undesirable side-effect of reducing air flow due to its bulk, and therefore be counter-productive by increasing the need for active cooling.
- Mounting fans on anti-vibration mounts.
- In energy-hungry computers, water cooling may be necessary for quiet operation. However, water pumps often make systems noisier than air-cooled, low-power computers.
Low/no cost methods:
- Undervolting CPUs. 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 varies as V*V*F, that is, linearly with the clock frequency but with the square of the voltage. This means that even small reduction in voltage can have large effect in power consumption. Undervolting and underclocking can also be used with chipsets and GPUs.
- Reducing fan voltages. This is easily done for fans with Molex connectors [1]. With 3-pin fans, either fixed inline resistors or diodes, or commercial variable resistors such as the Zalman Fanmate can be used. Many newer motherboards support Pulse-width modulation (PWM) control allowing the fan speed to be set in the BIOS or with software.
- Isolating hard disk noise either by using anti-vibration mounts (generally a rubber or silicone grommet), or suspending the hard disk to fully de-couple it from the PC chassis (generally mounting it in an 5.25" drive bay using high-grade elastic).
- Replacing the fan in the PSU for a quieter one (which still offer adequate airflow to cool the PSU), or undervolting it. Note that opening a PSU can be dangerous.
- Removing restrictive fan grills to allow easier airflow.
- Enabling Cool'n'Quiet for AMD K8 CPUs or EIST on a few of Intel's latest CPUs.
- Using software such as Nero Drivespeed to reduce the speed of optical drives.
- Setting hard drives to spin down after a short moment of inactivity (from Power Options in the Control Panel in Windows). However, for primary system drives Windows will access the hard drive itself every so often forcing the drive to restart, and so this is not so effective. It is more useful however for data storage drives, which may not be accessed often.
- Running Windows Disk Defragmenter on the hard drives to reduce the drive heads' need to search widely for data, also improves on performance.
- Setting the AAM value on to its lowest setting. Hitachi's Tool can be used for this. This reduces the seek noise produced by the hard drive, but also impacts performance slightly.
[edit] Individual components in a quiet PC
The following are notes regarding individual components in quiet PCs.
[edit] Hard drives
3.5", 7200 RPM ball-bearing hard drives were notorious for being extremely noisy. 5400 RPM ball-bearing hard drives were in general louder than 7200 RPM and 10000 RPM fluid bearing drives. All hard drive manufacturers have switched to fluid bearing motors in standard desktop hard drives. The first hard drive widely reputed to be quiet was the Seagate baracuda ATA IV. Samsung, Western Digital and Maxtor are considered to produce some of the quietest high capacity 3.5" drives as of Summer 2006, with noise varying per model[2].
Recently people have begun to incorporate smaller 2.5" laptop disk drives in a further effort for silence. These smaller drives generally have lesser performance and capacity, and cost considerably more per GB, but also substantially lower power requirements and noise emissions[3].
To minimize vibrations from a hard drive being transferred to, and amplified by, the case, hard drives can be suspended with elastics or placed on soft foam or Sorbothane.
[edit] Solid state storage
Solid state disk storage is believed to be the future for storage in PCs, and particularly interesting to those interested in silent PCs. It 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. Samsung launched first notebook with their own 32 GB SSD drives on May 23, 2006, the first consumer-oriented SSDs, but still far more expensive and at far lower capacities than traditional drives.
[edit] Compact Flash cards
A small number of people also use Compact Flash cards to load their OS. Adapters can be brought which connect to an IDE port or cable and allow the CF card to be seen by the PC as a normal hard drive. CF cards are also very small, allowing very 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 reads/writes to each sector; often specified as 100,000 MTBF. However, there are industry grade cards which specify a higher MTBF and technologies such as EWF 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 is 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. 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. By virtue of the fact that these have many OS components removed they are also less prone to viruses and other malware. The sustained transfer rate of current CF cards is a maximum of around 25MB/s, compared to an average of around 70MB/s for modern hard drives[4]. However, the speed of flash memory is increasing at a faster rate than that of hard drives, and they also have minimal seek times compared to hard drives, which rapidly increases the speed of loading many small files, and makes the PC seem more responsive therefore as most operations performed by the OS include small files. Due to the fast seek times CF cards also don't suffer from file system fragmentation like hard drives do. CF drives only operate in PIO mode, which will limit the maximum transfer speed of future CF cards. 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 config files and other frequently modified data on a 2.5" hard drive or i-RAM.
[edit] 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. This is much more difficult with Windows (as it sees USB drives as removable mass storage devices by default), however it is possible. 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 future thumb drives are limited by the USB bus, rather than PIO mode.
[edit] Gigabyte i-RAM
The i-RAM is a solid-storage solution which has four DIMM slots to allow regular PC RAM (DDR, or DDR2 with upcoming version 2) to be used to store data. It plugs into a regular SATA port and is seen by the PC as a normal hard drive, and may therefore be booted from directly. RAM offers vastly faster transfer rates, and shorter seek times, compared to traditional hard drives; 3 GB/s is standard; over 25 times faster. Whilst the i-RAM is highly bottlenecked by the SATA interface, it is still much faster, and does not lose its advantage with seek times. RAM however is volatile, so needs to be constantly powered to retain data. The i-RAM does this by plugging into a PCI slot, which powers it when the PC is plugged in. It also has a 16 hour battery, which operates when the PC is unplugged or there is a power outage (when it is off but still plugged in, it operates from the PCs standby power). The i-RAM is very expensive per GB, but offers not only a silent storage method, but significantly decreased boot times, increased responsiveness and performance, and so is also liked by performance PC enthusiasts.
[edit] Problems and solutions
All forms of affordable solid state storage offer relatively small amounts of capacity. Therefore, they are generally only used alone in a secondary PC, perhaps used for simpler tasks which do not use large amounts of data or large programs, such as web browsing or word processing, leaving games, professional level image, music, and video editing and storage, CAD and such for systems with secondary hard drives. Keeping the OS, often accessed files, and smaller programs 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 out of the way. Small USB drives or CF cards can be used to make the process of network booting easier also, if so desired.
[edit] Cases
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.
The inside of a case can be lined with dampening materials to serve several purposes:
- to attenuate the vibration of the case panels via extensional damping or constrained-layer damping.
- to reduce the amplitude of the vibration of the case panels by increasing their mass.
- to absorb airborne noise, such as with foam.
More obstructive fan grills increase pressure drop and lower airflow, necessitating 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 honeycombed fan grills which perform almost as well as wire grills and are far superior to the old style of stamped grill, although some cases come with wire grills.
Cases designed for low noise usually include reasonably quiet fans, and often come with a relatively quiet power supply.
[edit] CPUs
The heat output of a CPU can vary according to its brand and model - to be exact, its TDP. Intel's Pentium 4E, or so called Prescott is infamous for being one of the hottest CPUs on the market. On the other extreme, AMD's Athlon series are known for being very cool.
The heat produced by CPUs can be reduced greatly by undervolting, which may require underclocking as well. Underclocking by itself also reduces heat and power consumption somewhat. Modern CPUs often incorporate dynamic clock throttling to reduce the CPU clockspeed and core voltage when the processor is not in use, thus further reducing thermal output, such as Cool'n'Quiet and EIST.
[edit] Modern low power CPUs
- AMD K8. Newer steppings are better. 90 nm.
- Intel Core and Core 2 series
- Intel Pentium M and Celeron M (lacks SpeedStep)
- All VIA and transmeta.
[edit] Fans
Bearing noise and motor noise vary between different fan models and also often between different samples of the same model of fan.
Quiet PCs typically use low-speed 120 mm 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 controllers can be used to slow down fast fans and to precisely choose fan speed. Fan controllers can produce a fixed fan speed using an inline resistor or diode, or a variable fan speed using a potentiometer or Pulse Width Modulation (PWM). Resistor-based fan control feeds the fan a lower than standard voltage, while PWM fan control rapidly cycles between feeding the fan full voltage and no voltage. PWM fan control reduces rotational speed, but can also produce clicking sounds in some fan models. 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[5]. Most fans will run at 5 volts once they are spinning, but will often stall when trying to start at less than 7 V. Some simple standalone 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.
Nexus, Yate Loon and some Scythe fans are generally considered the quietest fans as of 2006. In situations where the resistance to flow is very low, like in free-air conditions, Noctua fans also perform very well. It must be noted that certain brands of fan are prone to unsavory "testing" methodologies, e.g noise output is measured at an unusually long distance. Two extensive comparative surveys have been posted by Silent PC Review ([6]) and MadShrimps ([7]).
[edit] Power supplies
PSUs are made quieter through the use of quieter fans, more intelligent fan controllers (ones for which the correlation between temperature and fan speed is more complex than linear), higher efficiency, which reduces waste heat and need for airflow, more effective heatsinks and through designs which allow air to flow through with less resistance. PSU Efficiency has been generally improving[8].
The electrical coils in power supplies can produce noise which can become noticeable when the PC is quietened to a significant extent.
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 usually voids the warranty.
Fanless power supplies are available, they are usually equipped with large passive heat sinks and rely on natural convection to dissipate heat. These power supplies usually have lower wattage ratings. It is also imperative that fan less power supplies be installed in a case with good ventilation.
A power supply can be made to run quieter by providing it with a cooler and/or less obstructed source of air, as the speed of the internal fan often relies on the temperature in the PSU, which is in turn affected by the temperature of the air intake source. The method of thermal zones is used in the Antec P180 to keep the air supplied to the PSU cool.
[edit] Motherboards
Most recent motherboards have built in PWM based fan control for one or two fans.
Motherboards can produce coil noise. Many modern motherboard chipsets have very hot northbridges, which may come with active cooling, usually a small, noisy fan, notably nForce4. Some motherboard manufacturers have got rid of this fan by incorporating large heatpipe coolers, however this is still heat which is radiated into the case, and therefore requires good case airflow.
[edit] Monitors
CRT monitors can produce coil noise, as can the power brick for an LCD monitor. LCD monitors tend to produce least whine when at 100% brightness.
[edit] Optical drives
Optical drives can be slowed down by software to quieten 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 bought which tend to be quieter, however this may be due to the fact that they tend to run at slower speeds (typically 24x CD speed, 8x DVD speed).
[edit] Watercooling
Watercooling, whilst quieter than similar highly overclocked PCs cooled with high airflow fans, are not generally considered to have the ability to be as quiet as the quietest forms of air cooling; essentially due to the fact that a watercooling setup usually needs not only a fan to cool the radiator, but a pump also, which is rarely quiet. It is also a greater technical challenge, and typically more expensive and difficult to set up. The Zalman Reserator tends to be seen as the quietest watercooling solution, which uses a large, passive, combined pump, radiator and reservoir.
[edit] Retail quiet PCs
Apple is considered a leader in the production of retail quiet PCs. The Apple G4 Cube had few moving parts and would be near-silent in operation if the old ball bearing hard drive were replaced and decoupled, and the Mac mini has only one fan and uses a laptop hard drive to achieve low noise emissions. Dell is considered to produce some quiet PCs by the standards of normal PC builders, however not of the standard of enthusiast silencer builds.
