Server System

Abstract

To provide a server system that does not cause problems in operation of a server device even when a temperature of outside air is high, thereby reducing a total electric power consumption amount of the server system and improving environmental adaptability of the server system.SOLUTION: A server system S includes a liquid immersion device 1 that accommodates a server device 6 and liquid L, a cooling water circulation device 3 that circulates cooling water R for exchanging heat with the liquid L, and a heat exchanger 5 that exchanges heat between the cooling water R and outside air. The liquid immersion device 1 has an inflow part 11 into which the liquid L flows and an outflow part 12 from which the liquid L flows out. A heat-resistant temperature of the server device 6 is 75°C or higher, and even if a temperature of the liquid L flowing into the inflow part 11 is 45°C or higher and 60°C or lower, the temperature of the liquid L flowing out from the outflow part 12 is 60°C or higher and lower than 75°C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a server system.

Background Art

[0002] Conventionally, a technique for cooling a server device by immersing it in a liquid has been known. Patent Document 1 discloses a liquid immersion cooling system in which an ICT device in a liquid immersion tank is cooled by a liquid immersion tank cooling liquid cooled by heat exchange between a primary cooling system refrigerant discharged to the outside air by a chiller and the liquid immersion tank cooling liquid through a heat exchanger.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, server devices used in data centers and the like have increased their power consumption per unit space along with the improvement of their performance, and how to perform their heat dissipation treatment has become an issue. In a state where servers with a large power consumption are concentrated, it becomes difficult to remove heat by normal air cooling, so technologies such as the above liquid immersion cooling have been considered.

[0005] Immersion cooling can be broadly categorized into single-phase immersion cooling, which directly cools the heat source with a cooled liquid, and two-phase immersion cooling, which utilizes the heat of vaporization for cooling. In the former, cooling is achieved through the temperature gap between the inflow temperature of the cooled liquid and the temperature of the heat-generating IT equipment, so it had to be used in a room where a stable temperature could be maintained. In the latter, heat is removed from the heat source by the boiling of the cooling liquid, so the boiling point of the liquid needs to be matched to the temperature of the heat source, which is typically around 50-60°C. Furthermore, the more compact and smaller the space in which the device for efficiently condensing the vaporized liquid needs to be, the lower the operating temperature needs to be.

[0006] Ultimately, regardless of the immersion cooling method used, it was necessary to operate the system in a server room where the temperature was controlled to around 25°C. Cooling a server room with air conditioning consumes a significant amount of energy, so it was desirable to minimize the use of air conditioning.

[0007] However, if the outside temperature rises and air conditioning is not used to reduce energy consumption, the temperature of the cooling water exchanging heat with the outside air cannot be sufficiently lowered, and the liquid cannot be cooled adequately. As a result, in two-phase immersion cooling, the evaporation rate increases, and condensation cannot keep up, causing problems with the cooling of the server equipment. In single-phase immersion cooling, there was a problem in that the temperature of the entire system could not be lowered to the operating temperature of the equipment.

[0008] In situations where the external temperature is high, one possible approach to cool the servers is to forcibly lower the temperature of the cooling water. However, lowering the temperature of the cooling water requires electricity to operate a large refrigeration system using condensers and evaporators. As a result, this also increases the power consumption of the server system.

[0009] Therefore, the present invention has been made in view of these points, and aims to provide a server system that does not experience problems in the operation of the server device even when the ambient temperature is high, thereby reducing the total power consumption of the server system and improving the environmental adaptability of the server system. [Means for solving the problem]

[0010] In a first embodiment of the present invention, a server system is provided comprising: an immersion device containing at least a part of a server device; a cooling liquid for cooling at least a part of the server device; a cooling water circulation device for circulating cooling water that exchanges heat with the cooling liquid; and a heat exchanger in which the cooling water exchanges heat between the cooling water and the outside air while the cooling water is in a liquid state, wherein the immersion device has an inlet into which the cooling liquid flows in from the cooling water circulation device and an outlet into which the cooling liquid, after heat exchange with the server device, flows out to the cooling water circulation device, and the heat resistance temperature of the server device is 75°C or higher, and even if the temperature of the cooling liquid flowing into the inlet is 45°C or higher and 60°C or lower, the temperature of the cooling liquid flowing out from the outlet is 60°C or higher and less than 75°C.

[0011] The amount of volatilization of the cooling liquid when maintained at 120°C for 24 hours may be 5% by mass or less.

[0012] The cooling liquid may contain an antioxidant. The cooling liquid may also contain an additive to suppress the odor of the oil.

[0013] The server device comprises a server device body having a processing unit having a processor and a storage device without a processor, and a network device for connecting the server device body to an external device. The cable connecting the server device body and the network device may be heat-resistant and oil-resistant. This is preferable because it reduces the possibility of the cable dissolving into the relatively high-temperature oil used to cool the server device.

[0014] Within the immersion apparatus, the server unit and the network device may be connected by a cable other than an optical cable. The cable material does not have to contain any of styrene rubber, ethylene propylene rubber, butyl rubber, or polyvinyl chloride. These materials have low heat resistance and oil resistance, so it is preferable that none of them be included as cable material.

[0015] The flash point of the cooling liquid may be 250°C or higher. The cooling liquid may also be an oil with a higher kinematic viscosity than the cooling water. Since cooling water, which has a lower kinematic viscosity than oil, is used for cooling by outside air, it is possible to use narrow piping to increase the surface area, thereby dispersing heat more effectively and cooling more efficiently.

[0016] The kinematic viscosity of the cooling liquid is 50 mm 2 The kinematic viscosity of the cooling liquid may be less than or equal to 35 mm². 2 It may be less than / s. The lower the kinematic viscosity of the oil, the better, but in order to ensure thermal conductivity, specific heat, and flash point, it is acceptable to use it as a cooling liquid for server equipment as long as these values ​​are below the specified threshold.

[0017] The thermal conductivity of the cooling liquid may be 0.13 W / (m·K) or higher. The thermal conductivity of the cooling liquid may be 0.15 W / (m·K) or higher.

[0018] Pigment ink may be used for printing on the cable and the server device. Although the pigment ink is printed by fusing with heat, the temperature is extremely high compared to the temperature of the liquid used to cool the server device, so there is no concern that the printed characters will dissolve in the liquid.

[0019] The server device body further includes a heat sink for cooling the arithmetic processing unit, and the arithmetic processing unit and the heat sink may be connected via an iron bonding material. [Effects of the Invention]

[0020] According to the present invention, even when the temperature of the outside air is high, a server system in which no problems occur in the operation of the server device is provided, thereby reducing the total power consumption of the server system and improving the environmental adaptability of the server system.

Brief Description of the Drawings

[0021] [Figure 1] The configuration of the server system according to this embodiment is schematically shown. [Figure 2] The physical property values of PAO 8 cSt, which is the liquid used in the prototype server system, are shown.

Embodiments for Carrying Out the Invention

[0022] [Configuration of Server System S] FIG. 1 is a diagram schematically showing the configuration of a server system S according to this embodiment.

[0023] The server system S includes a liquid immersion device 1, a liquid flow path 2, a cooling water circulation device 3, a cooling water flow path 4, and a heat exchanger 5. The liquid immersion device 1 is a device that houses at least a part of the server device 6 and the liquid L. The liquid L is a liquid that cools at least a part of the server device 6. The liquid L is, for example, oil. The liquid L includes, for example, polyalphaolefin.

[0024] As will be explained in more detail later, the server system S is configured such that when the temperature of the liquid L flowing into the inlet 11 of the immersion device 1 is between 45°C and 60°C, the temperature of the liquid L flowing out from the outlet 12 of the immersion device 1 is between 60°C and 75°C. By setting the heat resistance temperature and operating temperature of the server device 6 to 75°C, the temperature of the liquid L around the server device 6 can be kept to around 60°C or below, thereby bringing the temperature of the server device 6 inside the immersion device 1 to an operating temperature. Therefore, the server system S can be operated without operating any special equipment for forced cooling. Specifically, by keeping the temperature of the liquid L to around 60°C or below, the liquid L can be efficiently cooled to around 45°C using cooling water directly cooled at an ambient temperature of around 40°C or below, without operating any special equipment for forced cooling.

[0025] As a result, the server system S can be operated continuously without the need to install special equipment for forced cooling. In other words, by raising the operating temperature of the server device 6, it becomes possible to eliminate the use of air conditioning in the server room and refrigeration systems for cooling water and refrigerants, which were almost commonplace in the server technology field, thereby achieving the remarkable effect of significantly reducing total power consumption. The configuration of server device 6 will be described in detail below.

[0026] The server device 6 comprises a server device main unit 61 and a network device 62. The server device main unit 61 includes an arithmetic processing unit 611, a storage device 612, and a communication device 613 connected to the network device 62. The arithmetic processing unit 611 is a device having a processor. The arithmetic processing unit 611 is, for example, a CPU (Central Processing Unit) and executes programs stored in the storage device 612.

[0027] The storage device 612 is a device that does not have a processor. The storage device 612 includes, for example, ROM (Read Only Memory), RAM (Random Access Memory), and SSD (Solid State Drive). The storage device 612 stores the program that the arithmetic processing unit 611 executes.

[0028] The communication device 613 is a device for electrically connecting the server unit 61 to the network device 62 using an electrical cable 63. The communication device 613 includes, for example, a LAN card.

[0029] The network device 62 is a device for connecting the server unit 61 to an external device. The network device 62 may be, for example, a repeater hub, a switching hub, or a router.

[0030] The immersion device 1 has an inlet 11 and an outlet 12. The inlet 11 has an opening through which liquid L flows in from the cooling water circulation device 3. The outlet 12 has an opening through which liquid L, after heat exchange with the server device 6, flows out to the cooling water circulation device 3. Inside the immersion device 1, the server device 6 is cooled by heat exchange between the liquid L flowing in from the inlet 11 and the server device 6. On the other hand, the liquid L that flows into the immersion device 1 from the inlet 11 is heated by the server device 6 through heat exchange within the immersion device 1 and flows out from the outlet 12.

[0031] The liquid channel 2 is a channel through which liquid L passes. The liquid channel 2 is connected to the immersion device 1 via the cooling water circulation device 3. One end of the liquid channel 2 is connected to the inlet 11. The other end of the liquid channel 2 is connected to the outlet 12. A portion of the liquid channel 2 is located within the cooling water circulation device 3. Liquid L that flows out from the outlet 12 flows through the liquid channel 2 within the cooling water circulation device 3 and enters the immersion device 1 from the inlet 11.

[0032] The cooling water circulation device 3 is a device that circulates cooling water R, which exchanges heat with liquid L. Part of the liquid flow path 2 and part of the cooling water flow path 4 are provided within the cooling water circulation device 3. The cooling water circulation device 3 cools liquid L by exchanging heat between liquid L flowing in the liquid flow path 2 and cooling water R flowing in the cooling water flow path 4. Liquid L circulates between the immersion device 1 and the cooling water circulation device 3 by flowing through the liquid flow path 2 by a pump (not shown) provided within the cooling water circulation device 3. Liquid L that flows into the cooling water circulation device 3 is cooled by exchanging heat with cooling water R flowing in the cooling water flow path 4 and flows out toward the immersion device 1. The temperature of liquid L that is cooled in the cooling water circulation device 3 and flows toward the immersion device 1 is, for example, 60°C or lower.

[0033] The cooling water passage 4 is a passage through which the cooling water R passes. Part of the cooling water passage 4 is located within the cooling water circulation device 3. Another part of the cooling water passage 4 is located within the heat exchanger 5. The cooling water R circulates through the cooling water circulation device 3 and the heat exchanger 5. The cooling water R that flows into the cooling water circulation device 3 is heated by the liquid L flowing through the liquid passage 2 through heat exchange, and then flows out of the cooling water circulation device 3 towards the heat exchanger 5.

[0034] The heat exchanger 5 is a device that exchanges heat between the cooling water R and the outside air while the cooling water R is in a liquid state. The heat exchanger 5 is, for example, a free cooling system. The heat exchanger 5 does not have a refrigerator, such as one using a condenser or evaporator. Another part of the cooling water flow path 4 is provided inside the heat exchanger 5. The heat exchanger 5 cools the cooling water R by exchanging heat between the cooling water R flowing through the cooling water flow path 4 and the outside air. The cooling water R that flows into the heat exchanger 5 is cooled by exchanging heat with the outside air and then flows out towards the cooling water circulation device 3. During this time, the cooling water R is in a liquid state.

[0035] The cross-sectional area of ​​the liquid channel 2 is, for example, larger than the cross-sectional area of ​​the cooling water channel 4. By doing so, it is possible to reduce the power consumption of the pump while maintaining highly efficient heat exchange with the outside air, and to reduce the possibility of clogging of the cooling water channel 4 in the heat exchanger 5.

[0036] The processing unit 611, storage device 612, communication device 613, and network device 62 all have a heat resistance temperature of 75°C or higher. Furthermore, the temperature of the liquid L flowing into the inlet 11 is between 45°C and 60°C while the server device 6 is in operation. Also, when the temperature of the liquid L flowing into the inlet 11 is between 45°C and 60°C, the temperature of the liquid L flowing out from the outlet 12 is between 60°C and 75°C.

[0037] In the server system S, a server unit 61 has a processing unit 611, a storage device 612, and a communication device 613, all of which have a heat resistance temperature of 75°C or higher. The server unit 6 also includes a network device 62 and an immersion device 1 that contains liquid L. When the temperature of the liquid L flowing into the inlet 11 of the immersion device 1 is between 45°C and 60°C during the operation of the server unit 6, the temperature of the liquid L flowing out from the outlet 12 of the immersion device 1 is between 60°C and 75°C.

[0038] Since the heat resistance temperature of the server device 6 housed in the immersion device 1 is 75°C or higher, the server system S can cool the server device 6 even with a high-temperature liquid L of 45°C or higher. Therefore, it is not necessary to cool the temperature of the liquid L flowing into the inlet 11 to a low temperature (e.g., 45°C or lower) using, for example, a refrigerator. Furthermore, since the temperature of the liquid L flowing out from the outlet 12 is higher than that of the ambient air, even when the ambient temperature is high, the liquid L can be cooled by cooling water R that has exchanged heat with the ambient air without, for example, using a refrigerator.

[0039] Therefore, the server system S provides a server system S that does not experience problems operating the server device 6 even when the outside temperature is high, thereby reducing the total power consumption of the server system S and improving the environmental adaptability of the server system S.

[0040] [Details of Server Device 6] The server device 6 has an electrical cable 63. The electrical cable 63 is a component that connects the communication device 613 of the server device body 61 to the network device 62. The electrical cable 63 is heat-resistant and oil-resistant. In the server system S, the heat-resistant and oil-resistant properties of the electrical cable 63 make it difficult for a part of the electrical cable 63 (for example, a flexible material such as the coating) to dissolve into the liquid L even when it is at a high temperature.

[0041] The material of the heat-resistant and oil-resistant electrical cable 63 should preferably not contain any of the following: styrene rubber, ethylene propylene rubber, butyl rubber, or polyvinyl chloride. In the server system S, the provision of such an electrical cable 63 allows the electrical cable 63 to be manufactured from a material that is less susceptible to the effects of high-aniline oil. For example, polyalphaolefin-based oil exhibits similar properties to high-aniline oil and is therefore included in high-aniline oil. As a result, in the server system S, deterioration of the electrical cable 63 can be prevented even in polyalphaolefin-based oil at 60°C.

[0042] By connecting the server unit 61 and the network device 62 using only an electrical cable 63 instead of an optical fiber, it is possible to avoid connection errors caused by light refraction and scattering when these devices are placed in the liquid L. Furthermore, for communication from the network device 62 to the outside, the wiring from the immersion device 1 to the outside is done with an electrical cable, and the electrical signal is converted to an optical signal outside the liquid L, thereby avoiding connection errors in optical connections caused by the liquid L.

[0043] For example, pigment ink is used for printing on the electrical cable 63 and the server device 6. Pigment ink is used by dissolving it at a higher temperature during printing compared to, for example, dye ink. In the server system S, by using pigment ink, which has excellent heat resistance in this way, the print is less likely to melt even in the high-temperature liquid L.

[0044] The server unit body 61 has a heatsink 614. The heatsink 614 is a component for cooling the processing unit 611. The heatsink 614 is made of copper, for example, and has wider fins than a heatsink provided in a server unit that is cooled by an air-cooling fan, for example. The heatsink 614 does not have a fan for air cooling, for example.

[0045] The processing unit 611 and the heat sink 614 are connected via an iron adhesive. In the server system S, because the heat sink 614 is provided in this way, grease is not used to thermally connect the heat sink 614 and the heat-generating element, thus preventing the grease from melting into the high-temperature liquid L.

[0046] [Details of Liquid L] The following describes the desirable physical properties of liquid L. The flash point of liquid L is, for example, 250°C or higher. Because the server device 6 is immersed in liquid L, it will not ignite during operation at high temperatures. However, even if a small spark occurs due to damage to, for example, the chip of the processing unit 611, the possibility of the fire spreading can be reduced.

[0047] Liquid L is, for example, an oil with a higher kinematic viscosity than cooling water R. In the server system S, using oil as liquid L in this way improves safety due to the insulating properties of the oil.

[0048] The kinematic viscosity of liquid L is, for example, 50 mm². 2 It is less than or equal to / s. More preferably, the kinematic viscosity of the liquid L is, for example, 35 mm². 2 It may be less than / s. In the server system S, by using a liquid L with such kinematic viscosity, the lower the kinematic viscosity, the less pump power is required to circulate the liquid L, thus reducing power consumption.

[0049] The thermal conductivity of liquid L is, for example, 0.13 W / (m·K) or higher. More preferably, the thermal conductivity of liquid L may be, for example, 0.15 W / (m·K) or higher. In the server system S, using liquid L with such thermal conductivity improves cooling efficiency because a higher thermal conductivity indicates superior heat absorption capacity (speed of heat removal) of liquid L.

[0050] When liquid L is maintained at 120°C for 24 hours, the amount of volatilization is preferably, for example, 5% by mass or less. In server systems S, using liquid L with such a volatilization rate significantly reduces maintenance costs because liquid L is less likely to evaporate in high-temperature environments.

[0051] Liquid L contains, for example, an antioxidant. In the server system S, the inclusion of an antioxidant in liquid L makes it less susceptible to oxidation, thus preventing changes in the composition (chemical formula) of liquid L and thus preventing changes in its performance.

[0052] Liquid L contains, for example, an additive that suppresses the odor of oil. In the server system S, the inclusion of such an additive in liquid L suppresses the odor of oil, thereby reducing, for example, the psychological impact of the oil smell on maintenance personnel.

[0053] [Examples] Figure 2 shows the physical properties of PAO 8 cSt, the liquid L used in the prototype server system S. PAO 8 cSt is a type of polyalphaolefin oil.

[0054] The density of liquid L at 15°C is 0.8317 g / cm³. 3 The specific heat of liquid L at 40°C is 2.2 kJ / (kg·K). The thermal conductivity of liquid L at 40°C is 0.137 W / (m·K). The flash point of liquid L (measured by the COC method) is 260°C or higher. The kinematic viscosity of liquid L at 40°C is 46.91 mm³. 2The value is / s. The kinematic viscosity of liquid L at 100°C is 7.959 mm². 2 The rate of change is / s. The relative permittivity of liquid L at 25°C is 2.12. The amount of liquid L that evaporates when kept at 120°C for 24 hours is 3.7 wt% or less.

[0055] Furthermore, the liquid L shown in Figure 2 is designed to withstand year-round operation of the server system S during product deployment, ensuring that the data center can operate continuously even under the conditions of the highest and lowest ambient temperatures in summer and winter. The server operating conditions were set with an upper limit of 42°C for the highest ambient temperature, as the highest ambient temperature in Japan is 41.1°C, and a lower ambient temperature of -7°C, as the cold-climate specifications for heat pump water heaters stipulate performance indications under extremely low heating conditions: an ambient temperature of -7°C (JISC9220, etc.).

[0056] Furthermore, the various physical properties of the liquid L used to cool the server device 6 can be appropriately adjusted by using other polyalphaolefin-based oils or silicone oils, or by using various well-known additives. By achieving the above-mentioned desirable physical properties of the liquid in this way, it becomes possible to cool the server system S more efficiently.

[0057] [Effects of the server system S according to this embodiment] As described above, the server system S according to this embodiment includes a server device 6 having a processing unit 611, a storage device 612, and a network device 62, all of which have a heat resistance temperature of 75°C or higher, and an immersion device 1 that contains liquid L. When the temperature of the liquid L flowing into the inlet 11 of the immersion device 1 is 45°C or higher and 60°C or lower, the temperature of the liquid L flowing out from the outlet 12 of the immersion device 1 is 60°C or higher and less than 75°C.

[0058] As a result, in the server system S, the server device 6 can operate at a high temperature, so the server device 6 can be cooled with high-temperature liquid L. Therefore, it is not necessary to cool the temperature of the liquid L flowing into the inlet 11 to a low temperature (e.g., 45°C or below) using a refrigerator, for example. Also, because the temperature of the liquid L flowing out from the outlet 12 is high, even when the ambient temperature is high, the liquid L can be cooled using cooling water R that has exchanged heat with the ambient air, for example, without using a refrigerator.

[0059] Therefore, the server system S provides a server system S that does not experience problems operating the server device 6 even when the outside temperature is high, thereby reducing the total power consumption of the server system S and improving the environmental adaptability of the server system S.

[0060] Furthermore, this invention makes it possible to contribute to the United Nations-led Sustainable Development Goals (SDGs): Goal 7 "Affordable and Clean Energy," Goal 9 "Industry, Innovation and Infrastructure," and Goal 13 "Climate Action."

[0061] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combinations are combined with the effects of the original embodiments. [Explanation of symbols]

[0062] S... Server System 1...Liquid immersion equipment 11...Inflow part 12. Outlet 2. Liquid channel 3...Cooling water circulation device 4. Cooling water channel 5...Heat exchanger 6. Server equipment 61...Server unit 611... Arithmetic Processing Unit 612...Storage device 613...Communication device 614... Heatsink 62. Network devices 63... Electrical Cables

Claims

1. A liquid immersion device containing at least a part of a server device and a cooling liquid for cooling at least a part of the server device, A cooling water circulation device that circulates cooling water that exchanges heat with the aforementioned cooling liquid, A heat exchanger in which the cooling water, while in liquid state, exchanges heat between the cooling water and the outside air, It has, The aforementioned immersion apparatus is The cooling liquid flows into an inlet from the cooling water circulation device, An outlet section through which the cooling liquid, after heat exchange with the server device, flows out to the cooling water circulation device, It has, The heat resistance temperature of the server device is 75°C or higher. A server system in which, even if the temperature of the cooling liquid flowing into the inlet is 45°C or higher and 60°C or lower, the temperature of the cooling liquid flowing out from the outlet is 60°C or higher and less than 75°C.

2. The amount of evaporation of the cooling liquid when maintained at 120°C for 24 hours is 5% by mass or less. The server system according to claim 1.

3. The cooling liquid contains an antioxidant, The server system according to claim 1.

4. The cooling liquid contains an additive that suppresses the odor of the oil. The server system according to claim 1.

5. The server device is A server device main unit having a processing unit with a processor and a storage device without a processor, A network device for connecting the main body of the server device to an external device, It has, The cable connecting the server unit and the network device is heat-resistant and oil-resistant. The server system according to claim 1.

6. Within the immersion apparatus, the server unit and the network device are connected by a cable other than an optical cable. The server system according to claim 5.

7. The material of the cable does not contain any of styrene rubber, ethylene propylene rubber, butyl rubber, or polyvinyl chloride. The server system according to claim 5.

8. The flash point of the cooling liquid is 250°C or higher. The server system according to any one of claims 1 to 7.

9. The cooling liquid is an oil with a higher kinematic viscosity than the cooling water. The server system according to any one of claims 1 to 7.

10. The kinematic viscosity of the cooling liquid is 50 mm ２ / s or less, The server system according to claim 9.

11. The kinematic viscosity of the cooling liquid is 35 mm². ２ / s or less, The server system according to claim 10.

12. The thermal conductivity of the cooling liquid is 0.13 W / (m·K) or higher. The server system according to any one of claims 1 to 7.

13. The thermal conductivity of the cooling liquid is 0.15 W / (m·K) or higher. The server system according to claim 12.

14. Pigment ink is used for printing on the cable and the server device. The server system according to claim 5.

15. The server device body further includes a heat sink for cooling the processing unit, and the processing unit and the heat sink are connected via an iron bonding material. The server system according to claim 5.

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