Fan size
The diameter of the fan(s) used in the cooling system.
In general, larger fans are considered more advanced than smaller ones: they allow you to create a powerful air flow at a relatively low speed and low noise level. On the other hand, a large diameter means large dimensions, weight and price. As for specific figures,
40 mm and
60 mm models are considered miniature,
80 mm and
92 mm are medium,
120 mm and
135 /
140 mm are large, and even
200 mm fans are found in the most powerful
case systems.
Speed controller
—
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.Max. air flow
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.
Noise level
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.
Heat pipes
Number of heat pipes in the cooling system
The heat pipe is a hermetically sealed structure containing a low-boiling liquid. When one end of the tube is heated, this liquid evaporates and condenses at the other end, thus removing heat from the heating source and transferring it to the cooler. Nowadays, such devices are widely used mainly in processor cooling systems (see "Intended use") — they connect the substrate that is in direct contact with the CPU and the heatsink of the active cooler. Manufacturers select the number of tubes based on the overall performance of the cooler (see "Maximum TDP"); however, models with similar TDPs can still differ markedly in this parameter. In such cases, it is worth considering the following: increasing the number of heat pipes increases the efficiency of heat transfer, but also increases the dimensions, weight and cost of the entire structure.
As for the number, the simplest models provide
1 – 2 heat pipes, and in the most advanced and powerful processor systems, this number can be
7 or more.
Mount type
—
Latches. The simplest and most convenient type of fastening, in particular due to the fact that it does not require the use of additional tools. Plus, you don't need to remove the motherboard for snap-on installation.
— Double-
sided (backplate). This type of fastening is used in the most powerful and, as a result, heavy and large-sized cooling systems. Its feature is the presence of a plate installed on the opposite side of the motherboard — this plate is designed to protect against damage and so that the board does not bend under the weight of the structure.
—
Bolts. Fastening with classic bolts. It is considered somewhat more reliable than latches (see above), but less convenient, because. You can remove and install the cooling system only with a screwdriver. To date, bolts are mainly used to fasten case fans, as well as cooling systems for RAM and hard drives (see "Type", "Purpose").
—
Silicone mounts. The main advantage of silicone fasteners is good vibration absorption, which significantly reduces the noise level compared to similar systems using other types of fasteners. On the other hand, silicone is somewhat less reliable than bolts, so both types of fasteners are usually supplied in the kit, and the user chooses which ones to use.
— Adhesive tape. Fastening with adhesive tape (adhesi
...ve tape), usually double-sided. The main advantages of this mount are ease of use and compactness. On the other hand, it is difficult to remove such a cooling system. In addition, adhesive tape is inferior in thermal conductivity to the same thermal paste.Dimensions
General dimensions of the cooling system. For water systems (see "Type"), this paragraph indicates the size of the external radiator (the dimensions of the water block in such devices are small, and there is no need to specify them in particular).
In general, this is a fairly obvious parameter. We only note that for case fans (see ibid.), the thickness is of particular importance — it directly depends on how much space the device will take up inside the system unit. At the same time, it is customary to refer to
fans with a thin case for models in which this size does not exceed 20 mm.
Height
The cooling system should fit into the computer case without any problems. The vast majority of case manufacturers indicate in the specifications the maximum height of the cooler that can be installed on their chassis. It is from this value that it is necessary to build on when choosing a cooling system. With an oversized cooler, you will have to leave the side wall of the case wide open, which violates the built-in air circulation pattern and provokes dust pollution of the internal space of the system unit.