A computer fan can be any fan inside a computer case used for cooling purposes, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heatsink to cool a particular component. A mechanical fan is an electrically powered device used to produce an airflow for the purpose of creature comfort (particularly in the heat ventilation, exhaust A computer case (also known as the computer chassis, cabinet, tower, box, enclosure, housing or simply case A heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using Thermal contact (either direct or radiant The use of fans and/or other hardware to cool a computer is sometimes referred to as active cooling. Computer cooling is the process of removing heat from computer components
Manufacturers of fans include, among others, Akasa, Arctic Cooling, Cooler Master Delta, Nexus, Noctua, NorthQ, ebm-papst, Scythea and Zalman. The Akasa Group of companies is a manufacturer of computer components Arctic Cooling is a Swiss maker of coolers for computer components, most notably Heat sinks and fans. Cooler Master Co Ltd is a manufacturer of Computer cases Computer fans Heat sinks liquid cooling systems, and power supplies Zalman Tech Co is a Korean company that develops and provides aftermarket desktop computer products with primary focus on cooling enhancement
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Usage
As processors, graphics cards, RAM and other components in computers have increased in clock speed and power consumption, the amount of heat produced by these components as a side-effect of normal operation has also increased. A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to The clock rate is the fundamental rate in cycles per second (measured in Hertz) at which a Computer performs its most basic operations such as adding two The temperatures of these components need to be kept within a reasonable range to prevent overheating, instability, malfunction and damage leading to a shortened component lifespan.
While in earlier personal computers it was possible to cool most components using convection (passive cooling), more efficient cooling has become a necessity on many components. Convection in the most general terms refers to the movement of molecules within Fluids (i To cool these components, fans are used to move heated air away from the components and draw cooler air over them. Fans attached to components are usually used in combination with a heatsink to increase the surface area available for heat conduction, thereby improving the efficiency of cooling. A heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using Thermal contact (either direct or radiant
In the IBM compatible PC market, the computer's PSU (power supply unit) has always used an exhaust fan to expel warm air from the PSU. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Power supply is a reference to a source of Electrical power. A device or system that supplies Electrical or other types of Energy to an output load Active cooling on CPUs started to appear on the Intel 80486, and by 1997 was standard on all desktop processors[1]. The Intel 486, otherwise known as the 80486 i486 or just 486 was the first tightly pipelined X86 design Chassis or case fans, usually one exhaust fan to expel heated air from the rear and optionally an intake fan to draw cooler air in through the front, became common with the arrival of the Pentium 4 in late 2000[1]. The Pentium 4 brand refers to Intel 's line of single- core mainstream desktop and Laptop Central processing units (CPUs introduced A third vent fan in the side of the PC, often located over the CPU, is also common. The GPU (graphics processing unit) on many modern graphics cards requires a heatsink and fan. In some cases, the northbridge chip on the motherboard requires a fan and heatsink. The northbridge, also known as the memory controller hub ( MCH) in Intel systems (AMD VIA SiS and others usually use 'northbridge' is traditionally one A motherboard is the central or primary Printed circuit board (PCB making up a complex electronic system such as a modern Computer or Laptop Other components such as the RAM and hard drives may also be actively cooled, though as of 2007 this remains relatively unusual. A hard disk drive ( HDD) commonly referred to as a hard drive, hard disk, or fixed disk drive, is a Non-volatile storage device Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. It is not uncommon to find five or more fans in a modern PC. The most common RAM cooling application are RAM Heatsinks, which attach to the RAM itself. [1]
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Cooling fan applications
Case mount
Used to aerate the case of the computer. The components inside the case which use active cooling cannot remove heat efficiently if the surrounding air is too hot. Case fans move air through the case, usually drawing cooler outside air in through the front (where it may also be drawn over the internal hard drive racks) and expelling it through the rear. There may be a third fan in the side or top of the case to draw outside air into the vicinity of the CPU, which is usually the largest single generator of heat. Case fans are usually 80 mm, 92 mm or 120 mm along each side. Because case fans are often the most readily visible form of cooling on a PC, decorative fans are widely available and may be lit with LEDs or made of UV-reactive plastic. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Decorative grilles are also common. Decorative fans and accessories are popular with case modders. Case modification (commonly referred to as case modding) is the modification of a computer chassis (often just referred to as the case) or a Air filters are often used over intake fans, to prevent dust from entering the case. Dust is a general name for minute Solid particles with Diameters less than 500 micrometers.
Power Supply fan
A power supply (PSU) fan often plays a double role, not only keeping the PSU itself from overheating, but also removing warm air from inside the case. Power supply is a reference to a source of Electrical power. A device or system that supplies Electrical or other types of Energy to an output load Many modern PSUs expel the air from the rear, but only from the PSU itself. PSUs with two fans are also available, which have a large fan on the bottom for removing case air and a smaller one on the back for expelling the warm air at a faster rate.
CPU fan
Used to cool the CPU (central processing unit).
- See computer spot cooling. Computer cooling is the process of removing heat from computer components
Graphics card fan
Used to cool the GPU and/or memory on graphics cards. A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to These fans were not necessary on older cards because of their low heat dissipation, but most modern graphics cards, especially those designed for 3D graphics and gaming, need their own dedicated cooling fans. Some of the higher powered cards can produce more heat than the CPU (over 190 watts[2]), so efficient cooling is especially important. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. Passive coolers for new video cards, however, are not unheard of, such as the Thermalright HR-03. Thermalright is taiwan-based company that manufactures high-performance Heat sinks for desktop computers
Chipset fan
Used to cool the northbridge of a motherboard's chipset or for system bus overclocking. A chipset is a group of Integrated circuits or chips that are designed to work together and are usually marketed as a single product In Personal computers the Front Side Bus ( FSB) is the bus that carries data between the CPU and the northbridge.
Other types of fans
Other less commonly encountered fans may include:
- PCI slot fan: A fan mounted in one of the PCI slots, usually to supply additional cooling to the PCI and/or graphics cards. The Peripheral Component Interconnect, or PCI Standard (commonly PCI) specifies a Computer bus for attaching peripheral devices to a Computer
- Hard disk fan: A fan mounted next to or on a hard disk drive. This may be desirable on faster-spinning (e. g. 10,000 RPM) hard disks where heat production is higher.
- CD Burner fan: Some internal CD-ROM burners included cooling fans.
Physical characteristics
The width and height of these usually square fans are measured in millimeters; common sizes include 60 mm, 80 mm, 92 mm and 120 mm. Fans with a round frame are also available; these are usually designed so that one may use a larger fan than the mounting holes would otherwise allow (i. e. , a 120 mm fan with 90 mm holes). The amount of airflow which fans generate is typically measured in cubic-feet per minute (CFM), and the speed of rotation is measured in revolutions per minute (RPM). Often, computer enthusiasts choose fans which have a higher CFM rating, but produce less noise (measured in decibels, or dB), and some fans come with an adjustable RPM rating to produce less noise if the computer does not need much airflow. The decibel ( dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity relative to Fan speeds may be controlled manually (a simple potentiometer control, for example), thermally, or by the computer hardware or by software. Fan control is the management of the rotational speed of an electric fan typically a Computer fan, to provide adequate cooling while lowering Noise. A potentiometer is a three-terminal Resistor with a sliding contact that forms an adjustable Voltage divider.
The type of bearing used in a fan can affect its performance and noise output. A bearing is a device to permit constrained relative motion between two parts typically rotation or linear movement Most computer fans use one of the following bearing types:
- Sleeve bearing fans use two surfaces lubricated with oil or grease as a friction contact. Sleeve bearings are less durable as the contact surfaces can become rough and/or the lubricant dry up, eventually leading to failure. Sleeve bearings may be more likely to fail at higher temperatures, and may perform poorly when mounted in any orientation other than horizontally. The lifespan of a sleeve bearing fan may be around 40,000 hours at 50 °C. Fans that use sleeve bearings are generally cheaper than fans that use ball bearings, and are quieter at lower speeds early in their life, but can grow considerably noisier as they age. [3][4]
- Rifle bearing fans are similar to sleeve bearing, but are even quieter and have almost as much lifespan as ball bearings. The bearing has a spiral groove in it that pumps fluid from a reservoir. This allows them to be mounted vertically (unlike sleeve bearings), since the fluid being pumped lubricates the top of the shaft. [5] The pumping also ensures sufficient lubricant on the shaft, reducing noise, and increasing lifespan.
- Ball bearing fans use a sealed bearing containing steel balls against which the axle rotates. A ball bearing is an engineering term referring to a type of Rolling-element bearing which uses Balls to maintain the separation between the moving parts Though generally more expensive, ball bearing fans do not suffer the same orientation limitations as sleeve bearing fans, are more durable especially at higher temperatures, and quieter than sleeve bearing fans at higher rotation speeds. The lifespan of a ball bearing fan may be around 63,000 hours at 50 °C. [3][4]
- Fluid bearing fans have the advantages of near-silent operation and high life expectancy (comparable to ball bearing fans). Fluid bearings are bearings which solely support the bearing's loads on a thin layer of liquid or gas However, these fans tend to be the most expensive.
- Magnetic bearing or maglev fans, in which the fan is repelled from the bearing by magnetism. A magnetic bearing is a bearing which supports a load using Magnetic levitation.
Connector pin assignment
| P1 | Black | Ground | |
| P2 | Red | +12 V, +5 V, or 230 V in reverse order of importance | |
| P3 | Yellow | Speed sensor wire -usually open collector output (RPM) |
| P1 | Black | Ground | |
| P2 | Yellow | +12 V | |
| P3 | Green | Speed sensor wire (RPM) | |
| P4 | Blue | PWM (Pulse-width modulation) control wire |
The behaviour of a PWM fan plugged into a 3-pin header (i. Pulse-width modulation (PWM of a signal or power source involves the Modulation of its Duty cycle, to either convey information over a e. PWM signal disconnected) varies depending on model. Intel CPU coolers run at their fastest speed, as a failsafe (but can be slowed by connecting pins 4-1); others may run at the lowest speed (but can be operated at the fastest speed by joining pins 4-2) [2]
Alternatives
If a fan is not desirable, because of noise or reliability concerns, there are some alternatives:
- Underclocking/undervolting to reduce power dissipation (this is the inverse of the "diminishing returns" problem faced by overclockers)
- Larger heatsink (for example, some motherboards have northbridge fans; others have larger, more costly heatsinks)
- Convection cooling: carefully designed, correctly oriented, and sufficiently large CPU coolers can dissipate up to 100 W by convection alone. Underclocking also known as downclocking is the practice of modifying a synchronous circuit's speed settings to run at a lower Clock speed than the manufacturer's A heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using Thermal contact (either direct or radiant Convection in the most general terms refers to the movement of molecules within Fluids (i
- More unusual solutions, e. g. heatpipes bonded to the metal case, water cooling. Water cooling is a method of Heat removal from components As opposed to Air cooling, Water is used as the heat transmitter
See also
References
- ^ a b Mueller, Scott 2005. A mechanical fan is an electrically powered device used to produce an airflow for the purpose of creature comfort (particularly in the heat ventilation, exhaust A centrifugal fan (also squirrel-cage fan, as it looks like a Hamster wheel) is a mechanical device for moving Air or other Gases It has a Computer cooling is the process of removing heat from computer components Fan control is the management of the rotational speed of an electric fan typically a Computer fan, to provide adequate cooling while lowering Noise. 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 Upgrading and Repairing PCs. Que Publishing. 16th edition. pp 1274-1280
- ^ Nvidia's GeForce 9800 GX2 Launches. Retrieved on 2008-03-20. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1600 - The Linköping Bloodbath takes place on Maundy Thursday in Linköping, Sweden.
- ^ a b Williams, Melody. Ball vs Sleeve: A Comparison in Bearing Performance. Retrieved on 2007-10-30. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 637 - Antioch surrenders to the Muslim forces under Rashidun Caliphate after the Battle of Iron bridge.
- ^ a b Anatomy of the Silent Fan. Retrieved on 2007-04-09. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 193 - Septimius Severus is proclaimed Roman Emperor by the army in Illyricum (in the Balkans)
- ^ Coolermaster Neon LED Case Fans Review (2003-03-25). Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Events 1199 - Richard I is wounded by a crossbow bolt while fighting France which leads to his death on April 6. Retrieved on 2007-12-05. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 63 BC - Cicero reads the last of his Catiline Orations.
- ^ 4-Wire Pulse Width Modulation (PWM) Controlled Fans Specification
External links
- 4-Wire Pulse Width Modulation (PWM) Controlled Fans Revision 1. 3
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