Comparison Chieftec AF-1225PWM vs Xilence XF046

The type of bearing used in the cooling fan(s).

The bearing is the piece between the rotating axle of the fan and the fixed base that supports the axle and reduces friction. The following types of bearings are found in modern fans:

— Sliding. The action of these bearings is based on direct contact between two solid surfaces, carefully polished to reduce friction. Such devices are simple, reliable and durable, but their efficiency is rather low — rolling, and even more so the hydrodynamic and magnetic principle of operation (see below), provide much less friction.

— Rolling. They are also called "ball bearings", since the "intermediaries" between the axis of rotation and the fixed base are balls (less often — cylindrical rollers) fixed in a special ring. When the axis rotates, such balls roll between it and the base, due to which the friction force is very low — noticeably lower than in plain bearings. On the other hand, the design turns out to be more expensive and complex, and in terms of reliability it is somewhat inferior to both the same plain bearings and more advanced hydrodynamic devices (see below). Therefore, although rolling bearings are quite widespread nowadays, however, in general, they are much less common than the mentioned varieties.

— Hydrodynamic. Bearings of this type are filled with a special liquid; when rotate...d, it creates a layer on which the moving part of the bearing slides. In this way, direct contact between hard surfaces is avoided and friction is significantly reduced compared to previous types. Also, these bearings are quiet and very reliable. Of their shortcomings, a relatively high cost can be noted, but in fact this moment often turns out to be invisible against the background of the price of the entire system. Therefore, this option is extremely popular nowadays, it can be found in cooling systems of all levels — from low-cost to advanced.

— Magnetic centering. Bearings based on the principle of magnetic levitation: the rotating axis is "suspended" in a magnetic field. Thus, it is possible (as in hydrodynamic ones) to avoid contact between solid surfaces and further reduce friction. Considered the most advanced type of bearings, they are reliable and quiet, but expensive.

The highest speed at which the cooling system fan is capable of operating; for models without a speed controller (see below), this item indicates the nominal rotation speed. In the "slowest" modern fans, the maximum speed does not exceed 1000 rpm, in the "fastest" it can be up to 2500 rpm and even more.

Note that this parameter is closely related to the fan diameter (see above): the smaller the diameter, the higher the speed must be to achieve the desired airflow values. In this case, the rotation speed directly affects the level of noise and vibration. Therefore, it is believed that the required volume of air is best provided by large and relatively "slow" fans; and it makes sense to use "fast" small models where compactness is crucial. If we compare the speed of models of the same size, then higher speeds have a positive effect on performance, but increase not only the noise level, but also the price and power consumption.

— Auto (PWM). A type of automatic regulator used in processor cooling systems. The principle of this adjustment is that the automation monitors the current load on the CPU and adjusts the fan operation mode to it. Thus, the cooling system works "in advance": it actually prevents the temperature rise, and does not eliminate it (unlike the thermostat described below). The disadvantages of such automation are the high cost and additional compatibility requirements: the PWM function must be supported by the motherboard, and the fan must be powered through a 4-pin connector (see "Power").

— Manual. Manual regulator that allows you to set the rotation speed at the request of the user. Its main advantages are both the possibility of arbitrary adjustment and reliability: automation does not always respond optimally, and in performant systems it is sometimes better for the user to take control into his own hands. On the other hand, manual control is more expensive and also more difficult to use — it requires the user to pay more attention to the state of the system, and if not attentive, the likelihood of overheating increases significantly.

— Manual / auto. A combination of the two systems described above: the main control is carried out by PWM, and the manual regulator serves to limit the maximum rotational speed. A fairly convenient and advanced option that expands the possibilities of auto-adjustment and at the same time doe...s not require constant temperature control, as with a purely manual setting. However such functionality is expensive.

— Adapter (resistor). In this case, the speed is adjusted by reducing the voltage supplied to the fan. To do this, it is connected to the power supply through a resistor adapter. This is a kind of alternative to manual adjustment: adapters are inexpensive. On the other hand, they are much less convenient: the only way to change the rotation speed with such an adjustment is to actually change the adapter, and for this you have to turn off the system and climb into the case.

— Thermostat. Automatic speed control according to data from a sensor that measures the temperature of the cooled component: when the temperature rises, the intensity of work also increases, and vice versa. Such systems are simpler than the PWMs described above, moreover, they can be used for almost any system component, not only for CPU. On the other hand, they have more inertia and reaction time: if the PWM prevents heating in advance, then the thermostat is triggered by an increase in temperature that has already happened.

The maximum airflow that a cooling fan can create; measured in CFM — cubic feet per minute.

The higher the CFM number, the more efficient the fan. On the other hand, high performance requires either a large diameter (which affects the size and cost) or high speed (which increases the noise and vibration levels). Therefore, when choosing, it makes sense not to chase the maximum air flow, but to use special formulas that allow you to calculate the required number of CFM depending on the type and power of the cooled component and other parameters. Such formulas can be found in special sources. As for specific numbers, in the most modest systems, the performance does not exceed 30 CFM, and in the most powerful systems it can be up to 80 CFM and even more.

It is also worth considering that the actual value of the air flow at the highest speed is usually lower than the claimed maximum; see Static Pressure for details.

The standard noise level generated by the cooling system during operation. Usually, this paragraph indicates the maximum noise during normal operation, without overloads and other "extreme".

Note that the noise level is indicated in decibels, and this is a non-linear value. So it is easiest to evaluate the actual loudness using comparative tables. Here is a table for values found in modern cooling systems:

20 dB — barely audible sound (quiet whisper of a person at a distance of about 1 m, sound background in an open field outside the city in calm weather);
25 dB — very quiet (normal whisper at a distance of 1 m);
30 dB — quiet (wall clock). It is this noise that, according to sanitary standards, is the maximum allowable for constant sound sources at night (from 23.00 to 07.00). This means that if the computer is planned to sit at night, it is desirable that the volume of the cooling system does not exceed this value.
35 dB — conversation in an undertone, sound background in a quiet library;
40 dB — conversation, relatively quiet, but already in full voice. The maximum permissible noise level for residential premises in the daytime, from 7.00 to 23.00, according to sanitary standards. However, even the noisiest cooling systems usually do not reach this indicator, the maximum for such equipment is about 38 – 39 dB.

Type of power connector for the cooling system. Power is usually output through the motherboard, for this the following connectors are most often used:

— 3-pin. Three-pin connector; Today it is considered obsolete, but it is still widely used.

— 4-pin. Plug with 4 pins. Its main advantage is the ability to automatically adjust the rotation speed via PWM (for more details, see "Speed controller").

These two standards are mutually compatible: a 3-pin fan can be connected to a 4-pin connector on the motherboard, and vice versa (unless PWM is available in both cases).

Much less common are options such as 2-pin, installed in some inexpensive fans; 6-pin, used in cooling systems with RGB backlighting, which requires a rather powerful additional power supply; 7-pin and 8-pin, similar in their specifics to a 6-pin connector; as well as power supply via a standard MOLEX plug provided in separate case fans.

The presence of its own illumination in the design of the cooling system.

The backlight serves a purely aesthetic function — it gives the device a stylish appearance that blends well with other components in the original design. Thanks to this, such cooling systems are especially appreciated by gamers and fans of external PC modding — especially since the lighting can be different, and the most advanced models even provide backlight synchronization with other components (see below). On the other hand, this function does not affect the efficiency and performance, and the overall cost is inevitably affected, sometimes quite noticeably. Therefore, if the appearance does not play a fundamental role for you, the best choice, most likely, will be a cooling system without backlight.

The colour of the backlight installed in the cooling system.

See above for more details on the backlight itself. Also note here that in the illumination of modern cooling systems there is both one colour (most often red or blue, less often green, yellow, white or purple), and multi-colour systems such as RGB and ARGB. The choice of a single-colour backlight depends mainly on aesthetic preferences, but the last two varieties should be touched upon separately.

The basic principle of operation of both RGB and ARGB systems is the same: the design provides for a set of LEDs of three basic colours — red (Red), green (Green) and blue (Blue), and by changing the number and brightness of the included LEDs, you can not only intensity, but and tint of light. The difference between these options differs in functionality: RGB systems support a limited set of colours (usually up to one and a half dozen, or even less), while ARGB allows you to choose almost any shade from the entire available colour range. At the same time, both of them can support backlight synchronization (see below); in general, this function is not required for RGB and ARGB systems, but it is used almost exclusively in them.