Comparison Zalman CNPS11X Performa vs Zalman CNPS10X Performa ST

The maximum TDP provided by the cooling system. Note that this parameter is indicated only for solutions equipped with heatsinks (see "Type"); for separately made fans, the efficiency is determined by other parameters, primarily by the air flow values (see above).

TDP can be described as the amount of heat that a cooling system is able to remove from a serviced component. Accordingly, for the normal operation of the entire system, it is necessary that the TDP of the cooling system is not lower than the heat dissipation of this component (heat dissipation data is usually indicated in the detailed characteristics of the components). And it is best to select coolers with a power margin of at least 20 – 25% — this will give an additional guarantee in case of forced operation modes and emergency situations (including clogging of the case and reduced air exchange efficiency).

As for specific numbers, the most modest modern cooling systems provide TDP up to 100 W, the most advanced — up to 250 W and even higher.

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.

The lowest speed at which the cooling fan is capable of operating. Specified only for models with speed control (see below).

The lower the minimum speed (with the same maximum) — the wider the speed control range and the more you can slow down the fan when high performance is not needed (such a slowdown allows you to reduce energy consumption and noise level). On the other hand, an extensive range affects the cost accordingly.

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.

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 maximum static air pressure generated by the fan during operation.

This parameter is measured as follows: if the fan is installed on a blind pipe, from which there is no air outlet, and turned on for blowing, then the pressure reached in the pipe will correspond to the static one. In fact, this parameter determines the overall efficiency of the fan: the higher the static pressure (ceteris paribus), the easier it is for the fan to “push” the required amount of air through a space with high resistance, for example, through narrow slots of a radiator or through a case full of components.

Also, this parameter is used for some specific calculations, however, these calculations are quite complex and, usually, are not necessary for an ordinary user — they are associated with nuances that are relevant mainly for computer enthusiasts. You can read more about this in special sources.

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.

The type of contact between the heat pipes provided in the heatsink of the cooling system and the cooled components (usually the CPU). For more information about heat pipes, see above, and the types of contact can be as follows:

— Indirect. The classic version of the design: heat pipes pass through a metal (usually aluminium) base, which is directly adjacent to the surface of the chip. The advantage of such contact is the most even distribution of heat between the tubes, regardless of the physical size of the chip itself (the main thing is that it should not be larger than the sole). At the same time, the extra piece between the processor and the tubes inevitably increases thermal resistance and slightly reduces the overall cooling efficiency. In many systems, especially high-end ones, this drawback is compensated by various design solutions (primarily by the tightest connection of the tubes with the sole), but this, in turn, affects the cost.

— Direct. With direct contact, the heat pipes fit directly on the cooled chip, without an additional sole; for this, the surface of the tubes on the desired side is ground down to a plane. Due to the absence of intermediate parts, the thermal resistance at the places where the tubes fit is minimal, and at the same time, the radiator design itself is simpler and cheaper than with indirect contact. On the other hand, there are gaps between the heat...pipes, sometimes very large — as a result, the surface of the serviced chip is cooled unevenly. This is partly offset by the presence of a substrate (in this case, it fills these gaps) and the use of thermal paste, however, in terms of uniformity of heat removal, direct contact is still inevitably inferior to indirect contact. Therefore, this option is found mainly in inexpensive coolers, although it can also be used in fairly performant solutions.

The material from which the substrate of the cooling system is made is the surface that is in direct contact with the cooled component (most often the processor). This parameter is especially important for models with heat pipes (see above), although it can be specified for coolers without this function. Options can be as follows: aluminium, nickel-plated aluminium, copper, nickel-plated stranded. More about them.

— Aluminium. The traditional, most common backing material. At a relatively low cost, aluminium has good thermal conductivity characteristics, is easy to grind (required for a snug fit), and well resists scratches and other irregularities, as well as corrosion. However in terms of heat removal efficiency, this material is still inferior to copper — however, this becomes noticeable mainly in advanced systems that require the highest possible thermal conductivity.

— Copper. Copper is noticeably more expensive than aluminium, but this is offset by higher thermal conductivity and, accordingly, cooling efficiency. The noticeable disadvantages of this metal include some tendency to corrosion when exposed to moisture and certain substances. Therefore, pure copper is used relatively rarely — nickel-plated substrates are more common (see below).

— Nickel-plated copper. Copper substrate with an additional n...ickel coating. Such a coating increases resistance to corrosion and scratches, while it practically does not affect the thermal conductivity of the substrate and work efficiency. However this feature somewhat increases the price of the radiator, but it is found mainly in high-end cooling systems, where this moment is almost invisible against the background of the overall cost of the device.

— Nickel-plated aluminium. Aluminium substrate with an additional nickel coating. For aluminium in general, see above, and the coating makes the heatsink more resistant to corrosion, scratches, and burrs. On the other hand, it affects the cost, despite the fact that in fact, pure aluminium is often quite sufficient for efficient operation (especially since this metal itself is very resistant to corrosion). Therefore, this variant was not distributed.