If you have even a little experience assembling computer system units, then you may have probably noticed that sometimes processor cooling fan connectors and case fans have a different number of legs: 4 or 3. They are also called 4 pin and 3 pin, respectively. In relatively old system systems on motherboards, only the processor fan has 4 wires, the rest of the connectors are 3-pin. On modern motherboards based on the sixth or seventh generation intel processors, as a rule, only 4 are wired pin connectors, and 3 pins are already living out their short life and we will no longer see them in the next generations of coolers and fans.

What is the difference between three and four wired fans, besides the difference in the number of wires? Read the answer to this question later in this article.

Main differences between 4 Pin and 3 Pin fans

Three pin fan connector- these are three indicators (by the number of wires): power (5 or 12 volts), ground and signal. The signal wire transmits the speed of rotation of the fan impeller at a normal nominal voltage of 4 or 12 volts. In this mode, the fan speed is usually controlled by increasing or decreasing the voltage along the power cable.

Four pin fan connector is slightly different from the three pin connector because it has an additional (fourth) wire used to send control signals to the fan, which has a chip. The chip controls the rotation speed of the fan impeller.

Three wire and four wire connectors

Processor fans mounted on a copper or aluminum radiator (together a cooler) use either a three-wire or four-wire connector. Three-wire connectors are designed for small fans with low power consumption. Four-wire connectors are designed for processor fans with higher power consumption.

When connecting a three-wire fan to a four-pin connector on the motherboard, the fan will always rotate, because the motherboard will not have the ability to control the 3-pin fan and adjust the speed of the cooler.

When connecting a four-wire fan to a three-pin connector on the motherboard, the fan will operate without the ability to adjust the speed from the motherboard.

If suddenly the fan does not work, then you need to swap wires 3 and 4 so that the wire with speed control remains unused.

The motherboard has many connectors for connection various devices. This is the processor, video card, RAM and others. Sometimes, for some reason, they prefer to use non-built-in sound and network card, and separately installed in PCI And PCI-E connectors. There are usually no problems connecting them; just install the card in its slot. But sometimes there is a need to completely disassemble the computer and independently replace the motherboard for the purpose of an upgrade, or a burnt-out board with a similar new one. There is nothing super complicated about this, but, as with everything, there are some nuances. For the motherboard and the devices installed on it to work, you need to connect power to it. In motherboards manufactured before 2001-2002, power was supplied to the motherboards using the connector 20 pin.

Power connector 20-pin female

This connector had a special latch on the body to prevent spontaneous removal of the connector, for example, in the event of shaking during transportation. In the picture it is at the bottom.

With the advent of Pentium 4 processors, a second 4-pin 12 volt connector was added, connected separately to the motherboard. These connectors are called 20+4 pin. Around 2005, power supplies and motherboards began to go on sale 24+4 pin. This connector adds 4 more contacts (not to be confused with 4 pin 12 volts). They can be connected to a common connector and then 20 pin turn into 24 pin, or connect with a separate 4 pin connector.

This is done for power compatibility with older motherboards. But in order for the computer to turn on, it is not enough to supply power to the motherboard. This is in ancient computers that had AT format motherboards, the computer was turned on after power was supplied to the power supply, using a switch or a power button with a lock. In ATX format power supplies, to turn them on, you need to short-circuit the power supply terminals PS-ON And COM. By the way, you can check an ATX format power supply in this way by shorting these pins with a wire or an unbent paper clip.

Turning on the power supply

In this case, the power supply should turn on, the cooler will begin to rotate and voltage will appear at the connectors. When we press the power button, on the front panel system unit, we send a kind of signal to the motherboard that the computer needs to be turned on. Also, if we press the same button while the computer is running and hold it for about 4-5 seconds, the computer will turn off. Such a shutdown is undesirable because programs may malfunction.

Power switch connector

Computer power button ( Power) and reset button ( Reset) are connected to the computer motherboard using connectors Power switch And Reset switch. They look like two-pin black plastic connectors with two wires, white (or black) and colored. Using similar connectors, a power indication is connected to the motherboard, on a green LED, labeled on the connector as Power Led and a hard drive operation indicator on the red HDD Led.

Connector Power Led It is often divided into two connectors with one pin each. This is done due to the fact that on some motherboards these connectors are located next to each other, just like HDD Led, and on other boards they are separated by a pin space.

The figure above shows the connection of connectors Front panel or the front panel of the system unit. Let's look at the connection in more detail Front panel. Bottom row, on the left, the connectors for connecting the hard drive LED (HDD Led) are highlighted in red (plastic), followed by the connector SMI, highlighted in blue, then the connector for connecting the power button, highlighted in light green (Power Switch), followed by the reset button, highlighted in blue (Reset Switch). Top row, starting from the left, is the Power LED, dark green (Power Led), Keylock brown, and speaker orange (Speaker). When connecting the connectors of the Power Led, HDD Led and Speaker, the polarity must be observed.

Beginners also have many questions when connecting to the front panel USB connectors. The connector strip located on the back wall of the computer and the internal card reader are connected in the same way.

As can be seen from the two figures above, card readers and strips are connected using an 8-pin fused connector.

But USB connection Connecting connectors to the front panel is sometimes difficult because the pins of this connector are disconnected.

Connection USB to the motherboard - circuit diagram

They have markings similar to those we saw on the front panel connectors. As everyone knows, in USB connector 4 contacts are used: power supply +5 volts, ground and two contacts for data transmission D- and D+. In the connector for connecting to the motherboard we have 8 pins, 2 USB ports.

If the connector still consists of individual pins, the colors of the connected wires can be seen in the figure above. In addition to the power, reset, indication and USB connectors, the front panel has microphone and headphone jacks. These sockets are also connected to the motherboard with separate pins.

The connection of the sockets is organized in such a way that when you connect headphones, the speakers connected to the socket are disconnected Line-Out on the back of the motherboard. The connector to which the jacks on the front panel are connected is called FP_Audio, or Front Panel Audio. This connector can be seen in the figure:

The pinout or pin arrangement on the connector can be seen in the following figure:

fp audio connection

There is one caveat here if you used a case with jacks for a microphone and headphones, and then wanted to change to a case without such jacks. Accordingly, without connecting the connectors fp_audio to the motherboard. In this case, when connecting speakers to the connector Line-Out there will be no sound from the motherboard. In order for the built-in sound card to work, you need to install two jumpers (jumpers) on 2 pairs of contacts, as in the figure below:

Such jumpers - jumpers are used for installation on motherboards, video, sound cards and other devices for setting operating modes.

The structure of the jumper inside is very simple: it has two sockets that are connected to each other. Therefore, when we put a jumper on two adjacent pins - contacts, we close them together.

Also on motherboards there are soldered connectors for LPT and COM ports. In this case, for connection, use a strip with the corresponding connector on the rear wall of the system unit.

When installing, you need to be careful not to connect the connector incorrectly, on the contrary. Motherboards also have connectors for connecting coolers. Their number, depending on the motherboard model, is equal to two in cheap motherboard models, and up to three in more expensive ones. The processor cooler and the blow-out cooler located on the rear wall of the case are connected to these connectors. The third connector can be used to connect a cooler installed on the front wall of the system unit for blowing, or a cooler installed on the chipset radiator.

All these connectors are interchangeable, since they are mostly three-pin, with the exception of four-pin connectors for connecting processor coolers.

If you've already assembled computers yourself, you may have noticed that some PC models have four cooler legs, while others have three. What is the reason for this design feature and does it have any practical use, or is it just another invention of designers? If this feature is technical, then what is the difference between coolers with three and four legs? Let's try to answer this question.

Firstly, let's start with the fact that fans with different numbers of legs are more correctly called 3-pin And 4-pin. The described characteristic is technical and indicates the principle of operation of the cooler. Four-pin coolers are commonly found in modern motherboards. Also, four-pin coolers are most often used to cool the processor, while conventional ones can have three connectors. It is not so difficult to guess why this is needed.

Four-leg fans are more advanced because they support control of the impeller speed (by pulse width modulation method) , which is very important for proper cooling processor. This control is ensured precisely thanks to an additional fourth wire that transmits a signal from the control chip to the fan. Does this mean that three-pin fans do not have such control? No, they also have their own signal wire, only the speed of rotation of the impeller depends on changes in the voltage of the power cable, although it should be noted that in some cases the speed adjustment is purely symbolic.

If we take the picture as a whole, you should also pay attention to the number of connectors on the motherboard itself, because they also come in three-pin types. Depending on whether a three-pin and four-pin module is connected to a four-pin connector or vice versa, the fan will operate differently.

3-pin to 4-pin connector. Speed ​​adjustment is carried out by changing the output voltage, but it may also happen that the fan will spin constantly, since motherboard will not be able to control it.
4-pin to 4-pin connector. Full control of the rotation speed is provided based on the indicators taken into account by the control chip.
4-pin to 3-pin connector. A four-pin cooler connected to a three-pin connector may not work. Then you need to swap places 3 And 4 wires, leaving the cable responsible for speed control unused. But in any case, the rotation speed will not be controlled.

So, which fan is best to buy? The future is definitely for 4-pin propellers, so if there are four connectors on the motherboard, it is, of course, better to take them. The price is another matter; the latter can cost an order of magnitude more, so it all depends on the thickness of your wallet and the desire to have a more advanced cooling system.

Every home has a lot of computer fans: CPU coolers, video cards and PC power supplies. They can be used to replace burnt ones, or they can be connected directly to the power supply. There can be many applications for this: as a blower in hot weather, ventilation workplace from smoke when soldering, in electronic toys and so on.

Fans usually have standard sizes, of which the most popular today are 80 mm and 120 mm coolers. Their connection is also standardized, so all you need to know is the pinout of the 2, 3 and 4 pin connectors.

On modern motherboards based on the sixth or seventh generation intel processors As a rule, only 4 pin connectors are soldered, and 3 pin connectors are already a thing of the past, so we will only see them in older generations of coolers and fans. As for the location of their installation - on the power supply, video adapter or processor, this does not matter at all since the connection is standard and the main thing here is the pinout of the connector.

4 pin cooler wire pinout

Here the rotation speed can not only be read, but also changed. This is done using an impulse from the motherboard. It is capable of returning information to the tachogenerator in real time (the 3-pin one is incapable of this, since the sensor and controller are on the same power line).

3 pin cooler connector pinout

The most common type of fan is 3 pin. In addition to the negative and 12 volt wires, a third, “tacho” wire appears here. It sits directly on the sensor leg.

• Black wire - ground (Ground/-12V);
• Red wire - positive (+12V);
• Yellow wire - revolutions (RPM).

2 pin cooler wire pinout

The simplest cooler with two wires. The most common colors: black and red. Black - working negative of the board, red - 12 V power supply.

Here, the coils create a magnetic field that causes the rotor to spin within the magnetic field created by the magnet, and the Hall effect sensor evaluates the rotation (position) of the rotor.

How to connect a 3-pin cooler to a 4-pin

To connect a 3-pin cooler to a 4-pin connector on the motherboard in order to be able to programmatically adjust the speed, use the following diagram:

When a 3-wire fan is directly connected to a 4-pin connector on the motherboard, the fan will always rotate, because the motherboard will not have the ability to control the 3-pin fan and adjust the speed of the cooler.

Connecting the cooler to the power supply or battery

To connect to the power supply, use standard connectors, but if you need to change the number of revolutions (speed), you just need to reduce the voltage supplied to the cooler, and this is done very simply by rearranging the wires on the socket:

This way you can connect any fan, and the lower the voltage, the lower the speed, and therefore the quieter its operation. If the computer does not get very hot, but is very noisy, you can use this method.

To power it from batteries or rechargeable batteries, simply connect the plus to the red wire and the minus to the black wire of the cooler. It starts to rotate at 3 volts, the maximum speed will be somewhere around 15. You cannot increase the voltage any more - the motor windings will burn out from overheating. The current consumption will be approximately 50-100 milliamps.

PC cooler design and repair

In order to disassemble the fan, you need to remove the sticker on the side of the wires, opening access to the rubber plug, which we remove.

We pick up the plastic or metal half-ring with any object with a sharp end (a stationery knife, a flat-head screwdriver, etc.) and remove it from the shaft. A motor powered by DC according to the brushless principle. An all-metal magnet is attached to the plastic base of the rotor with an impeller in a circle around the shaft, and a magnetic circuit on a copper coil is attached to the stator.

Then clean the hole under the axle and drop a little machine oil there, put it back together, put in a plug (so that dust doesn’t get clogged) and continue using the much quieter fan.

All such fans have a brushless rotation mechanism: they are reliable, economical, quiet and have the ability to adjust the speed.

In modern coolers, the connectors are much smaller, where the first contact is numbered and is “minus”, the second is “plus”, the third transmits data about the current rotation speed of the impeller, and the fourth controls the rotation speed.

The size or diameter of the fan is measured in millimeters, for example, 120, 140, 92, 90, 80, 40, 50, 60, 200mm.
The thickness is usually from 15 to 40mm.

PC Fan Mount

In most cases, PC case fans are mounted on screws made of some kind of metal.

Some models come with rubber, silicone or other fasteners that reduce vibration and noise levels.

The fans are attached to the cooler radiator, most often using clamping frames or screws.

Types and types of bearings in PC fans

The type of bearing in a fan affects its performance and durability.

Bearings used in PC fans can be divided into two types: sliding and rolling, based on their operating principle.

Near the name, there are numbers indicating the approximate possible time between failures of the bearing under ideal conditions.

Plain bearings

Slip, simple(sleeve bearing) up to 35 t.h.
One of the most structurally simple plain bearings. Consists of a sleeve and a shaft. It deteriorates faster than others due to high friction of parts.

The service life directly depends on vibration loads and temperature conditions. The noise emitted is low, but due to rapid wear, it can reach levels that are unpleasant to the ear.

Hydrodynamic(FDB bearing) up to 80 t h
An improved version of the simple one. The space between the bushing and the shaft is filled with lubricant, minimizing friction, thereby significantly increasing service life and reducing noise levels.

Oil pressure(SSO) up to 160 t h
It differs from the previous one in that it has a magnet that centers the shaft, thanks to which wear is reduced, the volume of lubricant is increased, and as a result it is more durable and quiet.

Self-lubricating(LDP) up to 160 t h
A special, more viscous, liquid or solid lubricant, durable film or coating is used. Improved quality of processing of internal components...

With magnetic centering, levitation from -- - 160 to --
A practically contactless mechanism based on the principle of magnetic levitation.
Very quiet (Up to 80% quieter than others...), more reliable, better able to withstand use in aggressive environments.

Rolling bearings

Rolling bearing(ball bearing) up to 60 - 90 t h
Rolling bearings are theoretically a little noisier, but also more wear-resistant.
They consist of rings, rolling elements (balls or rollers), and a separator that holds the rolling elements in the desired position. The space between the bodies is filled with lubricant.

Ceramic(ceramic bearing) up to 160 t h
Manufactured using ceramic materials, withstands higher temperatures and has a lower noise level.

Types of fan connectors for PC

Warning!
If the fan has several different connectors for connection, then use only one of your choice, otherwise you may damage the devices.

3pin and 4 pin - pwn

General
Both are designed to connect to the motherboard.
For both connectors, the third contact is a tachometer, which determines the number of revolutions and a signal.
Both types are mutually compatible, that is, it is possible to connect 3pin to a 4pin connector and vice versa, observing the key. *

Differences between 3pin and 4pin
The difference between a 3pin and a 4pin connector is as follows:

U 3pin the number of revolutions is fixed, as a rule, this is the maximum value, which is usually not initially controlled in automatic mode.

U 4pin adjustment is carried out automatically, due to the received PWM signal from pin 4.

2pin

It is found inside power supplies, on video card boards and... It has only + 12V and grounding (-), speed control is possible and carried out by changing the voltage, with no information about the number of revolutions for the user.

Molex

Four-pin connector used to connect to the power supply. As a rule, only two of the 4 wires are involved, + and – from 12V. This means the fan operates at maximum speed.

*
If you connect a 3pin connector to a 4pin connector or vice versa, then adjustment based on the PWM principle will not be carried out. If the motherboard is capable of independently adjusting the speed through pin 3, by changing the voltage, then the adjustment will occur independently, if not, then it is possible to set a fixed number of revolutions in the BIOS, or leave it as it is, then the fan will work at maximum speed all the time .

Influence of parameters on fan operation

RPM- number of revolutions per minute.
CFM- the maximum possible air flow per minute in cubic feet.
The noise level is measured in sones - son or decibels - dBA. Quiet are considered to be values ​​up to 2000 rpm (RPM).

Example
Let's imagine two fans.

The example demonstrates (dependencies) that with a larger fan diameter and fewer revolutions, it is possible to obtain greater efficiency.

Backlight

Some models are equipped with lighting for decorative purposes. It can be either single-color, multi-color, or with the ability to choose a color and effect. The presence of backlight affects both the cost and energy consumption.