Processing board cooling system

Abstract

A cold-plate forming a circulating liquid cooled heat sink has a body 130 forming an inner volume having inlet and outlet chambers in fluid communication (see fig 4) with inlets and outlets of a jet impingement plate assembly 155, 530 (fig 5b). The body is enclosed by an outer cover plate 135. The cold-plate can be fixed to one side of a processor board 101 (such a PCB card with a GPU 104) and to a backing plate 110 on the opposite side of the board, so the board is sandwiched. The jet impingement plate is arranged over the hottest component, the processor. The other components are cooled by the rest of the cold-plate & backing plate assembly. Multiple cards, each with the heatsink assembly, maybe mounted side by side (figures 7,8)

Description

Technical Field The present application relates to cooling systems and in particular to liquid cooled heat sinks that provide concurrent cooling of multiple electrical components of a processing board. Background Electronic components generate heat when performing their electrical service. Some computer components, like central processing units, CPUs, and graphics processing units, GPUs, can generate a tremendous amount of heat in a relatively small area. If this heat is not extracted effectively, the processing units will heat to unsafe temperatures and fail. Within the context of a processing unit, it is known to provide these on dedicated processing boards. For example, a CPU is typically provided on a motherboard. These motherboards provide the necessary connections and support structures for the CPU to function within a computer system. The CPU socket on the motherboard is specifically designed to accommodate a particular type or family of CPUs, such as those based on Intel or AMD architectures. A GPU board, also known as a Graphics Processing Unit board, is a specialized circuit board designed to house a GPU (Graphics Processing Unit) along with associated components such as memory and power delivery systems. The GPU board is a critical component in a computer system, particularly in tasks that require intensive graphical processing, such as gaming, multimedia editing, scientific simulations, and artificial intelligence. It serves as the primary interface between the GPU and the rest of the computer, enabling the rendering and display of high-quality graphics and images. GPU boards come in various form factors and configurations, catering to different computing requirements and applications. Examples of GPUs include those manufactured by Nvidia. A GPU board interfaces with other computing components primarily through the motherboard and the system's central processing unit (CPU). Most modern GPU boards connect to the motherboard via a PCIe (Peripheral Component Interconnect Express) slot. The PCIe slot provides a high-speed data pathway for communication between the GPU board and the CPU. The GPU board typically requires its own power supply, which is connected either directly from the power supply unit (PSU) or via additional power connectors on the motherboard. This power supply provides the necessary electricity to operate the GPU and associated components. The operating system communicates with the GPU through specialized driver software. These drivers facilitate the interaction between the GPU and the CPU, enabling the system to utilize the GPU's processing power for graphical tasks. The GPU board typically features various display outputs, such as HDMI, DisplayPort, DVI, etc., allowing users to connect monitors or other display devices directly to the GPU for rendering output. The GPU board may also access system memory (RAM) for certain tasks. This is often referred to as shared memory or unified memory architecture, where the GPU can directly access system memory without going through the CPU, facilitating faster data transfer for certain computational tasks. Given the high processing power of modern GPUs, GPU boards typically include their own cooling solutions, such as fans or liquid cooling systems. These solutions dissipate the heat generated during operation to maintain optimal temperatures and prevent overheating. Overall, the GPU board works in conjunction with other computing components to accelerate graphical processing tasks, offloading the CPU and enhancing the system's overall performance in graphics-intensive applications. Recent developments in artificial intelligence have also resulted in deployments of multiple GPU within the same computing architecture. Some arrangements deploy two or more GPUs on a shared GPU board, other arrangements provide for multiple separate GPU boards to be coupled to the same shared motherboard concurrently. Despite the known architectures and solutions there continues to exist requirements to improve the cooling solutions that are deployed with GPU boards- particularly given the increased processing capacity of these GPUs and the resultant increased heat output. Summary These and other problems are addressed by a cooling system in accordance with the presented teaching. Accordingly, a first embodiment of the application provides a cooling system as detailed in claim 1. Advantageous embodiments are provided in the dependent claims. Brief Description Of The Drawings The present application will now be described with reference to the accompanying drawings in which: Figure 1 is a top view of a cooling system in accordance with the present teaching. Figure 2 is a bottom view of the system of Figure 1. Figure 3 is a bottom view of the system of Figure 1 with the backing plate 110 removed. Figure 4 is a perspective view showing the internal volume of the liquid cooled heat sink module of the system of Figure 1. Figure 5A is a section through the system of Figure 1 showing the components of the inlet chamber. Figure 5B is a detailed section through the system of Figure 1 showing the components of the inlet chamber. Figure 6 is a section through the system of Figure 1 showing the components of the outlet chamber. Figure 7 is a perspective view from one end of a plurality of stacked systems in accordance with the present teaching. Figure 8 is a perspective view from the other end of a plurality of stacked systems in accordance with the present teaching. Figure 9A is a side view of an assembled system including a processor board, showing exemplary height dimensions. Figure 9B is an exploded view of components of system including a processor board, showing the stacked components prior to assembly. Figure 10 is a graph showing GPU temperatures versus operational power for an exemplary system in accordance with the present teaching. Figure 11 is a graph showing GPU temperatures versus liquid flow rate through a liquid cooled heat sink for an exemplary system in accordance with the present teaching. Figure 12 is a top view of another embodiment of a cooling system in accordance with the present teaching. Figure 13 is a bottom view of the system of Figure 12. Figure 14 is a perspective view showing the internal volume of the liquid cooled heat sink module of the system of Figure 12. Figure 15 is a section through the system of Figure 12 showing the components of the inlet chamber. Figure 16 is a section through the system of Figure 12 showing the components of the outlet chamber. Detailed Description Figures 1 to 9B show an example of a first aspect of a cooling system 100 for providing cooling of multiple electronic components of a processor board 101 in accordance with the present teaching. The system 100 comprises a backing plate 110 and a liquid cooled heat sink 120. In this example the liquid cooled heat sink comprises a body portion 130 and a lid 135 which seal an internal volume 140 of the body portion. To improve the sealing arrangement one or more gaskets 102 may be seatable within the body 130 of the body portion and provide a seal to the internal volume once the lid 135 is presented to and mated against the body portion 130 As is evident from the perspective view of Figures, the liquid cooled heat sink comprises a body 130 defining an inner volume 140 comprising an inlet chamber 145 and an outlet chamber 150. The Figures includes arrows which are provided for illustrative purpose so as to clarify the direction that a fluid will flow through the liquid cooled heat sink. As is evident from the schematic, the inlet chamber 145 is in fluid communication with the outlet chamber 150 though at least one jet impingement plate 155 (in this embodiment a single jet impingement plate), such that operatively liquid enters the liquid cooled heat sink into the inlet chamber and passes through the at least one jet impingement plate prior to exiting the liquid cooled heat sink from the outlet chamber. The inlet chamber and outlet chamber have at least one fluid port through which fluid can enter and exit the inlet and outlet chambers respectively. In the example of Figure 3, first and second 160A, 160B inlet ports are provided, and first and second 161 A, 161B outlet ports are provided. The plurality of ports are provided to allow flexibility in choice as to how external fluid coupling can be attached to the system- as will be described later. Typically, only one of the plurality of inlet or outlet ports is used at any one time, the other being capped or otherwise sealed. These inlet and outlet ports define first and second pathways to each of the inlet chamber and outlet chamber, such that operatively fluid enters and exits the liquid cooled heat sink through a selected one of the first and second pathways. The backing plate 110 and liquid cooled heat sink 120 are configured so as to be coupled together in a stacked arrangement. They are respectively dimensioned such that when coupled together they define a volume within which a processor board 101 may be located. Typically the processor board 101 (shown in the views of Figure 9A and9B) will be mounted or otherwise affixed to the backing plate 110- the backing plate providing structural support for the processor board. It will be appreciated by those of ordinary skill that a processor board comprises a plurality of electronic components 103 including memory and at least one processing unit such as a Graphics Processing Unit, GPU 104. Such boards are typically interfaceable with other processing components of a computer system such as a motherboard and provide dedicated processing functionality. Examples of suppliers of such processor boards include Nvidia and Intel. The electronic components of the processor boards have dimensions that are dictated by their function and the layout of the boards themselves will determine regions of greater height than other regions. Per the present teaching, the backing plate 110 and liquid cooled heat sink 120 are configured to operatively sandwich a processor board 101 having a plurality of electronic components 103 including memory and at least one processing unit 104 provided thereon therebetween. To accommodate such a processor board, when the backing plate 110 and liquid cooled heat sink 120 are coupled together a region or space 500 is defined therebetween which has dimensions configured to accommodate the processor board 101 and its associated components 103. In addition, the body 130 of the liquid cooled heat sink 120 comprises conformal surfaces 510 configured to accommodate the sandwiched processor board and further comprising processing board facing surfaces 520 which, on sandwiching the processor, are configured to thermally contact at least a subset of the plurality of electronic components. The jet impingement plate 145 is located within the liquid cooled heat sink 130 so as to be coincident with an intended location a processing unit provided on a sandwiched processor board. In the example of Figures 1-5, the system is intended to be used with a processor board that has a single processing unit (in this exemplary arrangement a graphic processing unit, GPU). As can be seen from comparison of Figure 4 with each of Figures 5A, 5B, and 6, the conformal surfaces 510, 520 include conformal surfaces of the chambers 145, 150 corresponding to the processing board facing surfaces. As such the conformal surfaces of the chambers define regions of varying height within each of the chambers. The jet impingement plate 155 comprises a plurality of orifices 156 through which liquid operatively passes, the cooling system further comprising a cold plate 530 having a contoured surface 530A onto which the liquid passing through the plurality of orifices 156 operatively contacts. A jet impingement chamber 535 is desirably defined between the cold plate 530 and the jet impingement plate 266. Operatively a contact surface 530B of the cold plate 530 is provided in intimate contact with an upper surface of at least one of the at least one processing units. The cold plate is desirably provided separately to the body 130 of the liquid cooled heat sink but is operatively coupled to the liquid cooled heat sink. Where provided separately, a gasket 900 (shown in Figure 9b) may be provided between the cold plate 530 and the body portion 130 of the liquid cooled heat sink to ensure adequate sealing of the two, one to another. It will be appreciated that operationally the surfaces of the liquid cooled heat sink that are in thermal contact with corresponding components of the processor board function so as to thermally conduct the heat generated by those components into the body of the liquid cooled heat sink. That heat is then collected by the liquid passing through the liquid cooled heat sink. Within each of the inlet and outlet chambers, that heat transfer is effected simply by the passage of the liquid through the chambers. In contrast in the jet impingement chamber there is an active direction of heat from the jet impingement plate onto the cold plate 530 that more effectively causes a cooling of that surface. As such it will be understood that the liquid cooled heat sink comprises regions of differing thermal efficacy. Desirably the region of greatest efficiency will be co-located with the processing unit of the processor board, as it is that unit that operationally generated the greatest amount of heat. It is also that unit that requires active cooling so as to maintain its operational temperatures within defined parameters. It will be understood that given that the processor board is sandwiched between the liquid cooled heatsink and the backing plate that desirably each of these have a footprint greater than a footprint of the processor board with which the system is intended to be used. In this way, when the processor board is sandwiched, its perimeter is protected by the perimeter of each of the backing plate and the liquid cooled heatsink. As was referenced above, the liquid cooled heat sink has conformal surfaces that are configured to accommodate components of differing heights on a provided processor board. These conformal surfaces define one or more stepped regions on the processor facing surfaces of the liquid cooled heatsink. Correspond surfaces are provided within the chambers defined in the body of the liquid cooled heat sink. In this way the chambers are dimensioned to accommodate variations in height of individual electronic components of a processor board operatively sandwiched between the liquid cooled heat sink and the backing plate. As shown schematically in Figure 4, the liquid cooled heat sink 120 has a longitudinal axis 400 and wherein the inlet chamber 145 and the outlet chamber 150 are symmetrical about the longitudinal axis 400. In this configuration the at least one jet impingement plate 155 extends across the longitudinal axis 400. This corresponds to the typical location of a GPU on a processor board, where the unit will be located along the midline of the processor unit. As shown in Figure 7 and 8, when fully assembled individual cooling systems 100 can be stacked side by side - in this example three cooling systems are provided side by side. Each of the cooling systems are configured to accommodate and provide dedicated cooling to an individual processor board. In this example, the stacked three cooling systems provide independent cooling to three separate processor boards- each of which are provided with direct cooling. Each of the three individual processor boards can be directedly and independently electronically connected to other components of a server system- such as a motherboard. This can be advantageously achieved by ensuring that the dimensions are of backing plate and liquid cooled heat sink are such that on sandwiching a processor board between the backing plate and the liquid cooled heat sink, at least a portion of a Peripheral Component Interconnect Express, PCIE, 700 of the processor board projects is accessible to allow presentation of the processor board to a receiving slot of a motherboard. Power and other electrical ports can also be provided independently through other ports 710. An individual mounting bracket 720 for each cooling system 100. It will be appreciated, from the exemplary dimensions that are detailed in the sectional view of Figure 9A and the exploded view of 9B, that the sandwich arrangement that is provided by the present teaching allows for a reduced thickness and advantageously the overall thickness of a system when fully assembled (liquid cooled heat sink block plus GPU processor board plus backplate) is less than the standard single slot width (20.07mm). As such individual cooling of stacked processor boards can be provided within a conventional server configuration. It will be recalled from the discussion above that a plurality of plurality of ports 160, 161 are desirably provided to allow flexibility in choice as to how external fluid coupling can be attached to the system. Figure 8 shows an example of this flexibility where fluid connectors 800 are coupled to neighbouring systems in a staggered arrangement so as to maintain the stack in a relatively tight configuration. The thermal performance of a cooling system in accordance with the present teaching was tested and data is presented below in Table 1 Stress test Flow Rate l / min tnlet 1 Temperature °C GPU Power W 1 GPU Temperature °C Hot Spot Temperature °C Idle 5 20 9.0 20.7 29.7 60% 5 20 280.4 28.7 34.6 100% 5 20 445.7 36.2 43.4 100% 4 20 446.2 37.1 44.4 100% 3 20 446.6 39 46.8 100% 2 20 4 (5.4 41.3 49.6 100% 1 20 4 4 b. 6 46.2 56.2 100% 0.5 20 •'145.9 53.4 64.1 Table 1 It can be seen that for a variety of test conditions and operating stresses, that a cooling system per the present teaching maintains overall GPU processor temperature below 60 degrees centigrade, even at very low flow rates. This data is replicated graphically in each of Figures 10 and 11 which show graphs of performance showing how GPU temperature may vary for different operating powers and flow rates respectively. In each instance, the inlet water temperature was provided at a constant 20 degrees centigrade, and in Figure 11 the GPU power was maintained at 446 W. It is evident that the system of the present teaching achieves stable performances across a variety of operating conditions and parameters. The data set in Table 2 expands upon that of Table 1 in that it shows that whilst a reduction in flow rates through the liquid cooled heat sink may affect the temperature of the fluid leaving the block, the cooling is still effective to maintain the operational temperature of the GPU processor below 60 degrees centigrade. Flow rate L / min T inlet °C T outlet °C GPU power W GPU T "C Hot spot T °C Pump power W 4.8 20 21.0 278.0 28.5 33.8 21.6 4 20 21.2 273.0 23.7 34.2 13.9 3 20 21.7 278.0 29.4 34.9 7.0 2 20 22.6 278.0 30.7 36.0 2.9 1 20 25.5 278.0 33.7 39.2 1.1 4.8 20 22.1 445.0 36.0 42.3 21.6 4 20 22.8 445.0 36.8 43.0 13.8 3 20 23.7 445.0 38.0 44.6 6.7 2 20 25.1 445.0 40.1 47.4 2.8 1 20 28.5 445.0 44.9 53.8 1.1 Table 2 The consumption of power evidently reduces with lower pump rates, and as such there is a trade off between operational energy usage and the cooling effect required. For that reason, it will be appreciated that control algorithms may be deployed to monitor temperature of one or more of fluid through the system and / or the operational temperature of the GPU block so as to minimize pump power consumption to advantageously improve the energy efficiency of the cooling operation. Figures 12 to 16 show another example of a cooling system 1200 for providing cooling of multiple electronic components of a processor board in accordance with the present teaching. Where components are similar in function to that described above, the same reference numerals will be used. Again, and as described above, the system 1200 comprises a backing plate 110 and a liquid cooled heat sink 120. In this example again the liquid cooled heat sink comprises a body portion 130 and a lid 135 which seals an internal volume 140 of the body portion 130. The internal volume 140 comprises an inlet chamber 145 and an outlet chamber 150. As before, these two chambers are in fluid communication with one another but differing from the earlier embodiment the fluid path from the inlet chamber to the outlet chamber passes through two, as opposed to one, jet impingement plate 155. It will be recalled from above, that the location of the jet impingement plate is arranged so as to be co-located with a dedicated processing unit that is provided on a processing board that is supported by the backing plate 110. This embodiment is configured to be useable with boards having two processing units, and provides dedicated jet cooling regions for each of the two processing units. In effect, as opposed to having one high intensity cooling region this embodiment is configured to provide two dedicated cooling regions- each for a respective chip. Similarly to that described above, the body 130 of the liquid cooled heat sink 120 of this embodiment also includes conformal surfaces 510 that are configured to accommodate electronic components provided on the processor board. Once sandwiched between the backing plate and the liquid cooled heat sink, a processor board that is provided on the backing plate 110 will have certain components that are brought into intimate thermal contact with the conformal surfaces of the liquid cooled heat sink. This thermal contact will allow heat generated by those components to be thermally conducted through the body of the liquid cooled heat sink where it will be transported out of the system by the fluid that is passing through the liquid cooled heatsink. Evidently the cooling effect that is achieved by the direct jet impingement of the fluid onto the cold plate will be greater than that which is simply achieved by a liquid flowing through either of the inlet or outlet chambers. However, by having these regions of different cooling efficacy, the cooling system of the present teaching can provide effective cooling where required- without requiring additional air cooling of the components through active fan activated passage of air passed the components on the processor board. This embodiment also illustrates an alternative fluid inlet and outlet configuration,. Different to that described previously, in this arrangement the fluid inlet 160 and fluid outlet 161 are in the surfaces of the body 130 of the heat sink 120 that extend along its length, as opposed to its width- which was the configuration of the previous embodiment. It will be understood that the placement of the inlet and outlet in this configuration is exemplary of the flexibility that can be provided by a system per the present teaching where it is possible to modify the fluid coupling orientations to accommodate external variables such as available piping routes for the liquid cooling loop that is providing the liquid to the internal volume of the liquid cooled heat sink In addition to the improved cooling that is achieved using the cooling system of the present teaching, noise performance was also noticeably better using units per the present teaching as opposed to air cooled only units per the known art approach. It will be appreciated that exemplary aspects of a cooling system that comprises a liquid cooled heat sink have been described. The liquid cooled heat sink comprises a body defining an inner volume comprising an inlet chamber and an outlet chamber, the inlet chamber being in fluid communication with the outlet chamber though at least one jet impingement plate, such that operatively liquid enters the liquid cooled heat sink into the inlet chamber and passes through the at last one jet impingement plate prior to exiting the liquid cooled heat sink from the outlet chamber. The system is configured to effectively sandwich a processor board between the liquid cooled heat sink and a backing plate so as to effectively thermally conduct heat generated by components of the processor board through the body of the liquid cooled heat sink into a fluid that is passing through that body. Whilst the detailed description has provided examples of such a cooling system, it will be appreciated that modifications can be made without departing from the scope of the present teaching which is intended to be limited only insofar as is deemed necessary in light of the claims that follow. The words comprises / comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. Further, references throughout the specification to “the invention” are nonlimiting, and it should be noted that claim limitations presented herein are not meant to describe the invention as a whole. 5 Moreover, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein.

Claims

We claim:

1. A cooling system for providing cooling of multiple electronic components of a processor board, the system comprising:a backing plate, anda liquid cooled heat sink, the liquid cooled heat sink comprising a body defining an inner volume comprising an inlet chamber and an outlet chamber, the inlet chamber being in fluid communication with the outlet chamber though at least one jet impingement plate, such that operatively liquid enters the liquid cooled heat sink into the inlet chamber and passes through the at least one jet impingement plate prior to exiting the liquid cooled heat sink from the outlet chamber;wherein the backing plate and liquid cooled heat sink are configured to operatively sandwich a processor board having a plurality of electronic components including memory and at least one processing unit provided thereon therebetween, the body of the liquid cooled heat sink comprising conformal surfaces configured to accommodate the sandwiched processor board and further comprising processing board facing surfaces which, on sandwiching the processor board, are configured to thermally contact at least a subset of the plurality of electronic components.

2. The cooling system of claim 1 wherein the jet impingement plate is located within the liquid cooled heat sink so as to be coincident with an intended location of at least one of the at least one processing units on a sandwiched processor board.

3. The cooling system of claim 1 or 2 wherein the at least one processing unit is a graphic processing unit.

4. The cooling system of any preceding claim wherein the conformal surfaces include conformal surfaces of the chambers corresponding to the processing board facing surfaces.

5. The cooling system of claim 4 wherein the conformal surfaces of the chambers define regions of varying height within each of the chambers.

6. The cooling system of any preceding claim wherein the jet impingement plate comprises a plurality of orifices through which liquid operatively passes, the cooling system further comprising a cold plate having a contoured surface on which the liquid passing through the plurality of orifices operatively contacts.

7. The cooling system of claim 6 further comprising a jet impingement chamber defined between the cold plate and the jet impingement plate.

8. The cooling system of claim 6 or 7 wherein operatively a contact surface of the cold plate is provided in intimate contact with an upper surface of at least one of the at least one processing units.

9. The cooling system of any one of claims 6 to 8 wherein the cold plate is provided separately to the liquid cooled heat sink but is operatively coupled to the liquid cooled heat sink.

10. The cooling system of any preceding claim wherein the liquid cooled heat sink comprises regions of differing thermal efficacy.

11. The cooling system of any preceding claim wherein liquid cooled heat sink has a footprint greater than a footprint of the processor board with which the system is intended to be used.

12. The cooling system of any preceding claim wherein the chambers are dimensioned to accommodate variations in height of individual electronic components of a processor board operatively sandwiched between the liquid cooled heat sink and the backing plate.

13. The cooling system of any preceding claim wherein the liquid cooled heat sink has a longitudinal axis and wherein the inlet chamber and the outlet chamber are symmetrical about the longitudinal axis.

14. The cooling system of claim 13 wherein the at least one jet impingement plate extends across the longitudinal axis.

15. The cooling system of any preceding claim comprising first and second pathways to each of the inlet chamber and outlet chamber, such that operatively fluid enters and exits the liquid cooled heat sink through a selected one of the first and second pathways.

16. The cooling system of any preceding claim dimensioned such that on sandwiching a processor board between the backing plate and the liquid cooled heat sink, at least a portion of a Peripheral Component Interconnect Express of the processor board projects beyond a footprint of the system to allow presentation of the processor board to a receiving slot of a motherboard.

17. The cooling system of any preceding claim wherein the backing plate and liquid cooled heat sink are configured to be coupled to one another to effect the sandwiching of the processor board therebetween.

18. The cooling system of any preceding claim wherein the backing plate and liquid cooled heat sink define a first set of backing plate and liquid cooled heat sink, the system comprising a second set of backing plate and liquid cooled heat sink, the second set of backing plate and liquid cooled heat sink being configured to sandwich a second processor board therebetween, and wherein each of the first set and the second set are configured to being arranged relative to one another in an array so as to accommodate a coupling of multiple liquid cooled processor board concurrently to a shared mother board.

19. The cooling system of any preceding claim comprising first and second jet impingement plates, such that operatively liquid enters the liquid cooled heat sink into the inlet chamber and passes through at least one of the first and second jet impingement plates prior to exiting the liquid cooled heat sink from5 the outlet chamber.

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