The influence of the cooling system on the efficiency of thermal management and the performance of computer components

The article attempts to evaluate the existing methods of cooling computer components in terms of ensuring their efficient operation. Issues related to heat exchange were discussed and individual computer components were characterized in terms of heat reception and the available methods of cooling computer components were reviewed. Based on the analysis of cooling methods, the most appropriate solution was selected in terms of: efficiency, costs and generated noise. A liquid cooling system was designed for the model computer, allowing for a significant increase in the clock speed of the computer’s main components. In order to determine the efficiency of the system, i.e. the maximum flow that can be discharged by the system, and to determine the efficiency of the required coolers, appropriate calculations were made regarding: thermal conductivity between each of the cooled elements and the corresponding block and heat transfer to the cooling liquid inside each of the blocks.


Introduction
Computer operation is based on the need to process large amounts of data.The greater the computing power required of the computer's components to perform operations, the more energy is required by the individual components.The efficiency of the computer is relatively high, so that a large amount of electricity consumed is converted into work.[1] Unfortunately, a certain portion is converted into heat energy, resulting in an increase in the temperature of working systems.Overheating of computer components results in more or less serious consequences, which include: louder than usual operation of fans, lowering of processor clocking when a critical temperature value is reached, and, ultimately, permanent damage to computer components.[2][3][4] The cooling system of a computer is therefore an extremely important segment, which has an impact on creating optimal conditions for the operation of the CPU chip, its performance, and protecting components from damage associated with possible overheating.There are several methods of cooling computer components, of which we can distinguish two main subcategories: passive cooling and active cooling.[5] The passive cooling system is based solely on a metal heat sink or a heat sink with heat pipes.[6] The heat sink is most often aluminum or copper with a special ribbed design to increase the surface area involved in heat transfer.More sophisticated designs are equipped with heat pipes that use the phenomenon of convection.Active cooling is a development of the concept of passive cooling.It usually includes an aluminum heat sink and a fan or group of fans.The purpose of the fan is to force air through the finned part of the heat sink, which, as in passive cooling, plays the role of a medium that receives heat energy from the component requiring cooling.The active system, compared to the passive system, is characterized by a much higher efficiency, unfortunately, it is accompanied by the noise produced by the fans, which can be annoying in terms of working comfort.[7,8] Liquid cooling [9,10] is an indirect cooling system, which somewhat resembles the system used in automobiles.It consists primarily of a water block, water pump, radiator and the appropriate thickness of hoses.In addition, you can find in such systems: a reservoir, a flow meter, a thermometer and other devices that do not affect performance, but allow you to operate it more comfortably.While the installation of liquid cooling for a single component does not pose a great problem, as there are many solutions available on the market for most of the publicly available components offered by various manufacturers, the construction of a complete set providing adequate cooling for the processor, graphics card, RAM modules and motherboard is already quite a challenge, requiring adequate knowledge and experience.
The issue of heat dissipation from individual computer components, including the selection of a cooling system for comfortable operation, is therefore an extremely important and topical issue.With this in mind, the article deals with the development of a cooling system for the basic components of the computer, which will allow to increase the computer's ability to overclock and will be characterized by quiet working.

Design of the cooling system for the main components of the computer
The objective was to develop a highly efficient cooling system that would allow the computer to achieve relatively high efficiency and stable and safe working parameters.The system should also feature quiet functioning and be adjustable.In addition, the system should be characterized by simplicity of construction and low operating costs.The amount of financial outlay associated with the implementation of the system (the cost of purchasing individual components of the cooling system) and the overall dimensions of the individual components were considered secondary issues.The assumed increase in performance and stability of operation, refers to the computer used for graphics development, video rendering and 3D applications such as computer games.The setup requires a high level of cooling for the graphics card and CPU.

Analysis of possible cooling system solutions
Three most popular cooling methods were selected for analysis: passive cooling (concept 1), active cooling (concept 2) and liquid cooling (concept 3).The choice of cooling method was based on the weighted sum method.[11,12] The following comparison criteria were adopted: (1) efficiency -the ability to dissipate a large amount of heat flux, (2) work culture -very low noise level and impact on the contamination of the computer case, (3) control -the ability to adjust the intensity of operation depending on the demand; (4) manufacturing cost -the amount of money to be spent on the construction of the system, (5) operating cost -the amount of money to be spent on regular operation and maintenance of the system, (6) ease of implementation -the technical sophistication of the employee making the system, (7) dimensions -the dimensions of the system.
Before proceeding to evaluate each of the proposed concepts, it was determined in advance which of the evaluation criteria were prioritized (table 1).For this purpose, equation (1) was used to determine the target weighting index and equation ( 2) to help determine how many decisions are required to compare all criteria with each other.

𝑊𝑊𝑘 =
(1) where: WWk -criterion weight indicator, Sp -total points, Dt -number of decisions where: n -number of elements (criteria) compared Decision 1 compares the first two criteria with each other and determines which is the higher priority.Decision 2 addresses the second and third criteria, and Decision 3 addresses the third and fourth criteria.Once the first six decisions have been made, the comparison begins again with the change that now the first criteria are compared with the third, the second with the fourth, and so on.The steps should be carried out until all criteria are compared with each other, in this case 21 decisions.The next step, after determining the criterion weighting index, is to determine which concept most closely reflects the criterion (table 2).For this purpose, the following correlations were used: where: WWkk -concept weight indicator within each criterion, Sp -total points, Dk -number of decisions where: n -number of elements (concept) compared As in the case of determining the weight indicator of the WWk criterion, decisions were made to compare the three available concepts.Then the obtained points are summed up and the concept weight indicator is calculated.

Table 2. Determination of the weighting index of the concept evaluation criterion
No. criterion No. concept Then, based on equation ( 5), the concept point coefficient Wp was calculated (table 3).After a detailed analysis of all the advantages and disadvantages of each solution, the decision was made to design a cooling system based on liquid cooling technology.This concept received the highest score of 0.43 with a significant advantage over the other two solutions.The system provides very high performance allowing the computer to work in harsh conditions without the need to aircondition the room.The disadvantage of such a system is the area it occupies and the cost of its implementation.

Cooling system design
Based on the assumptions and analysis made, a liquid cooling system was designed, as shown in figure 1.

Thermal and flow analysis of the designed cooling system
In order to determine the efficiency of the system, basic calculations were carried out to determine the value of the heat stream that each of the blocks used can maximally dissipate, as well as their total heat stream value.Determining the sum value of heat stream facilitates the correct selection of coolers and fans.
To calculate the value of the heat stream, the equation ( 6) was used.Equation ( 7) was used to calculate the amount of heat transferred or received.Table 4 lists the values of the thermal conductivity coefficient λ for thermal paste and aluminium and the heat penetration factor α for water.The dimensions of the various computer components involved in heat exchange are listed in table 5.The results of the calculations are summarized in table 6.For proper operation of the system, it is required to select a suitable pump-cooler unit with a thermal capacity equal to or greater than 700 W. In the case of the present project, these are two coolers with a thermal capacity of about 350 W each and one pump.The assumed technical parameters of the components will allow for the dissipation of heat flux in excess of the required value, which will allow for smooth and quiet operation, even when using the overclocking values of its operation.

Conclusions
Based on the results of a comparative analysis of three methods of cooling computer components: active cooling, passive cooling and liquid cooling, the method was selected that meets the established criteria to the highest degree -the liquid cooling system.A liquid cooling system was designed for the model computer.In order to determine the performance of the system, i.e. the maximum flux that the system is capable of dissipating, and to determine the performance of the required coolers, relevant calculations were made regarding: the thermal conductivity between each cooled component and the corresponding block, and the heat penetration of the cooling liquid inside each block.Based on these calculations, a stream value of 675.16 W was obtained, and two coolers with a capacity of 350 W each were selected, making a total of 700 W. From the results obtained, it can be concluded that the element that limits the heat flow is the water block, since the heat flux that enters it is more than twice as high -amounting to 1469.97 W -as that which is absorbed by the cooling liquid.The developed cooling system can be improved, and in particular, the water blocks used should be improved, which do not allow more heat flow, thus reducing the efficiency of the system.In the paper, no calculations were made on the noise level during operation of the entire system due to the lack of access to relevant information on the total compression of the fans, which are the main noise generator in the system.

Table 1 .
Determination of the weighting index of the concept evaluation criterion

Table 3 .
The concept's scoring factor

Table 4 .
The values of the coefficients λ and α

Table 5 .
Dimensions of various components of the computer

Table 6 .
Summary of heat stream values for various components of the computer