A quiet, silent or fanless PC is a personal computer that makes very little or no noise. Common uses for quiet PCs include video editing, sound mixing and home theater PCs, but noise reduction techniques can also be used to greatly reduce the noise from servers. There is currently no standard definition for a "quiet PC", and the term is generally not used in a business context, but by individuals and the businesses catering to them.
A proposed general definition is that the sound emitted by such PCs should not exceed 30 dBA, but 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 in relation to a particular environment or set of users.
History Energy Star, in 1992, and similar programs led to the widespread adoption of sleep mode among consumer electronics, and the TCO Certified program promoted lower energy consumption.
Causes of noise The main causes of PC noise are: Vibration from disk drives Air vortex effects from fan blade edgesNoise Generation Mechanisms"Acoustic noise", jmcproducts.com Electrical whine: noise generated by electrical coils or transformers used in power supplies, motherboards, video cards or LCD monitors.
Measuring noise 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.
Noise reduction methods
Common noise reduction methods Use large, efficient heat sinks Incorporate heat pipes, which have much higher effective thermal conductivity than solid copper Use fans with lower speeds and larger diameters Use fans with low bearing and motor noise Rather than constant-speed fans, use thermostatically controlled variable-speed fans that run at less than maximum speed, and thus run quieter most of the time Use an efficient power supply to minimize waste heat Use quieter models of hard drive Use solid state devices like compact flash or solid-state drives rather than traditional mechanical hard drives Use remote networked via SMB or NFS rather than local disks Place a damping material such as Sorbothane around hard drives or other spinning items Use sound insulation material to absorb sound and dampen case resonance Water cooling, although difficult to set up, may be useful in some situations
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. 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 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 can be used. Software like speedfan or Argus Monitor 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.
In some cases an acceptable solution may be to relocate the too-noisy computer outside the immediate working area and access it either with long-distance HDMI/USB/DVI cables or via remote desktop software from a quiet thin client, e.g. based on a Raspberry Pi, a miniature computer that does not even use a heat sink.
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.
Motherboard
A motherboard based on a chipset that uses less energy will be easier to cool quietly. Undervolting and underclocking generally require motherboard support, but when available can be used to reduce energy use and heat output, and therefore cooling requirements.
Many modern motherboard chipsets have hot northbridges which may come with active cooling in the form of a small, noisy fan. Some motherboard manufacturers have replaced these fans by incorporating large heat sinks or heatpipe coolers, however they still require good case airflow to remove heat. Motherboard voltage regulators also often have heat sinks and may need airflow to ensure adequate cooling.
Some motherboards can control the fan speed using an integrated hardware monitoring chip (often a function within a Super I/O solution), which can be configured through BIOS or with a system monitoring software like SpeedFan and Argus Monitor, and most recent motherboards have built-in PWM fan control for one or two fans.
Even though a given hardware monitoring chip may be capable of performing fan control, a motherboard manufacturer may not necessarily wire up the fan header pins of the motherboard correctly to the hardware monitoring chip, thus sometimes computer fan control cannot be performed on a given motherboard due to the wiring irregularities, even though the software may indicate that the fan control is available due to the underlying support by the hardware monitoring chip itself. Alt URL Other times, it may be the case that a single fan-control setting may affect all fan connector headers on the motherboard at the same time, even if individual settings for each fan are available in the hardware monitoring chip itself; these wiring issues being very common makes it difficult to design good general-purpose user interfaces for configuring fan control.
Motherboards can also produce audible electromagnetic noise.
CPU 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 (newer versions, such as 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. AMD 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).
Video card
Video cards can produce a significant amount of heat. A fast GPU may be the largest power consumer in a computer and because of space limitations, video card coolers often use small fans running at high speeds, making them noisy.
Options to reduce noise from this source include: Replace the stock cooler with an aftermarket one.. Use motherboard video output. Typically, motherboard video takes less power but provides lower gaming or HD video decoding performance. Select a video card that does not use a fan. Most modern graphics cards come with tools that allow the user to reduce the power target and adjust fan curves, resulting in quieter operation at the cost of performance
Power supply
Power supply (PSU) is 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 heat sinks, and designs that 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.