Guide to selecting fans for the chassis - Reviews and guides
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Guide to selecting fans for the chassis


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Select fans for the chassis

Parameters for comparing fans
Connection type
There are 3 main connection types:
Connecting the 2 pins (including connecting directly to the power supply using a connection to the hub) - Connection including 2 Wires:  
Usually a red wire that transmits voltage, usually 12V and a color that is usually black that transmits soil (0V voltage), such fans operate at a constant speed and do not provide information about their rotation speed.

Connecting an 3 pin - A connection that includes the same wires as connecting an 2 pin and a third wire that passes the tach signal (tachometer), which transmits a quadratic signal whose frequency is proportional to the rotation speed of the fan.

Connecting an 4 pin - A connection that includes the same wires as an 3 pin connector plus a fourth wire used for PWM control (Pulse Width Modulation) and allows the motherboard or fan controller to control the fan's rotation speed.


Rotational speed
The fan rotation speed is measured in RPM (short for Revolutions Per Minute) and it indicates how many rotations the fan completes in one minute. The greater the rotational speed of the fan, the more noise it makes.


Fan size
Length or width of the fan frame in millimeters. Since most of the ventilators have a square frame, the value should be the same.
The most common fan size is probably 120 mm, but there are also fans of other sizes - 80 mm, 92 mm, 140 mm and more.



The amount of air (airflow) that a fan "pushes" depends on its size and rotation speed.
Larger fans spinning at the same speed as smaller fans will push more air. Hence, larger fans can be operated at a lower speed to push the same amount of air, thus reducing the noise level. The only thing that limits the use of larger fans is the size of the fans supported by the chassis.


Noise level
The noise level produced by the fan is usually measured in dBA (decibel level). This value usually appears as a parameter of the fan (on its packaging or on the manufacturer's page), but it must be taken with limited tolerance as different impulses measure the noise level of the fan in different forms.
In general, fans become less stable with time and therefore older fans tend to be more noisy.



When buying 140 or more fans, there is no problem with noise, since they usually rotate relatively slowly - simply buy fans with noise levels between 19dBA and 25dBA.


Air thrust / CFM
Cubic Feet / Minute shortcut. This parameter indicates how much air the fan can push for a minute (in cube units with a one foot leg, one foot equivalent to 0.3048 meters). This is usually the main parameter that indicates fan performance.


Static Pressure
Static pressure is measured in units of mmH2O (millimeter of water). In general, the larger the value of this parameter, the more power the fan can exert on an object.
This parameter is significant when you want a fan to be installed where its airflow will be blocked by an object (such as the processor heat sink, hard drive cage, Water, etc.). In such a case, a fan with a static pressure parameter should be preferred.


In general, a larger airflow fan will be more efficient when nothing is blocking the fan while a larger static fan will be more efficient when air is required to move through an object.


Power Consumption
Power consumption indicates how much power the fan will use.
The fan usually has a value indicating its current consumption in ampere (A). To calculate the power consumption of the fan, this value should be multiplied by the voltage at which the fan works (usually 12V). The resulting value is the power consumption of the Watts fan.
For example: If the fan has a maximum current consumption of 0.15A and works at maximum 12V voltage, the maximum power consumption of the fan is 12V X 0.15A = 1.8 Watts.


Some users want to match the colors of their computer system to a certain color scheme. In this case, fans of a certain color and / or LED fans can be chosen to match the fans to the desired color scheme.


life span
The number of hours in which the fan can work at continuous work at temperatures of 40-50 ° C.


Setup direction
The axis where you want to install the fan.

Bearing Type
The type of bearing used in the fan. The common bearings are Sleeve, Ball and Fluid Dynamic.


Sleeves are the most common because of their simplicity and cheap price.
In these bearings, two surfaces are used, including oil or grease, as a shielding agent to reduce the friction at high speeds.


Fans using such a terminal are usually cheaper than fans using ball bearing bearings.


life span:
The life span of 30,000 is at temperatures of 50 ° C.
The life span is slightly smaller than the ball bearing bearings at low environmental temperatures.
The life span of fans using a sleeve will be considerably longer if installed vertically (due to the way their internal lubrication system works).


Noise level:
Quiet at the beginning of their lives at low speeds but may become disabling with time.
Tend to develop "whining" noise over time when installed horizontally and will play faster.


Installation direction:
Do not function well when installed in any direction other than vertical.


Working at high temperatures:
Tend to spoil at high temperatures. Because the shielding material dries.
Fail immediately at temperatures above 70 ° C.
In an environment with a reasonable temperature, an optimal ratio of noise to price is given.


It is not profitable to invest in carrying out their maintenance - it is better to simply replace them (it is cheaper).
Tend to fail catastrophically without warning.


Bearings Rifle
Noise level:
Similar to the Sleeves but quieter.


life span:
The lifespan is almost like that of ball bearings.


Installation direction:
They can be installed horizontally without fear.


Ball Bearings
More expensive compared to the sleeve bearings.


life span:
A life span of approximately 60,000 hours at a temperature of 50 ° C.


Noise level:
Slightly noisier than Sleeve bearings at low rotational speeds.
Slightly quieter than the Sleeves


Installation direction:
There is no preferred installation direction.


Working at high temperatures:
More resistant to high temperatures than sleeve bearings.
The oiling system can fail over time, resulting in increased noise levels (especially at high temperatures).
Recommended working temperature - less than 70-80 ° C.


Fluid bearings
More expensive than ball bearings.

life span:
Longer life than ball bearings.
The lifetime of 100,000 hours at temperatures of 40-70 ° C and even more than 300,000 hours for some fans.


Noise level:
Almost completely silent throughout their lives.


Installation direction:
Can be installed in any direction.


Other names for these bearings are Fluid dynamic and Hydro.

Sources: guides/cpu fan tacho/cpu fan tacho.html

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Thanks for the article.

Another method for changing speed by changing voltage.

Some panels can control the speed of fans even when there are 2 or 3 pins by changing voltage, in 2 pins simply do not see the rpm.

I also read at the time by the writer of the software speed fan that you can perform PWM without the fourth thread, it is less effective, obviously it sounds unlikely I will search the link.

In the ball bearing fan the increase in noise over time is relatively small.

About FDB

In principle, this name has a patent. It is a sleeve bearing with grooves inside the bearing to increase lubrication.

There are different designs with similar names with grooves on the outside of the bearing, which are actually rifle bearing, or similar design.

Rather than FDB.

Edited By none77
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