Liquid Cooling Saves Cost and Increases Data Center Performance

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By: Faheem Karim, General Manager – EMEA at Supermicro

In the data center, the most powerful CPUs and GPUs are running hotter than ever. Although the performance of these microprocessors is increasing, the ability of air to cool the chips is reaching its limits. Liquid cooling is a technology in different forms that can keep the latest (and future) CPUs and GPUs cool and reduce operating costs in a data center.

Typically, a server is designed so that powerful fans draw the cool air from the front of the server, referred to as the inlet air, over the hot components. As CPUs are given work to do, they become hotter and need to be constantly cooled. Even with modern heat sinks, the operating temperature of the CPUs needs to be monitored closely. Liquid cooling is an alternative cooling technology that uses the capabilities of liquids to remove the heat from the chips. There are three main ways to use liquid cooling in modern severs.

Faheem Karim, General Manager – EMEA at Supermicro

Direct to Chip: In this method, which is popular, the cold liquid is pumped over a chip in a closed-loop mechanism. The liquid heats up as it passes over the chip and is then pumped to another chip or a cooling mechanism. A cooling mechanism can reside in a rack, within the data center, or outside of the data center. Depending on the CPUs and GPUs selected and the workloads, this technique may be the best option for removing the heat. In addition, Direct To Chip cooling reduces data center costs. For example, the Computer Room Air Conditioners (CRAC) do not have to run at the capacity of non-liquid-cooled data centers, and the fans within the servers can be scaled down significantly.

Immersive Cooling: The most efficient liquid cooling option is to totally immerse the server (with minor modifications) into liquid. The servers are submerged in a thermally conductive dielectric liquid or coolant. The heat from the CPUs is carried away, and the warmer liquid is then cooled outside of the submersion container. The cooler liquid is then pumped back to the container, where more heat can be carried away. This liquid cooling method is the most efficient, as liquid surrounds every component. However, an infrastructure needs to be set up to cool the warm liquid in a closed loop.

Rear Door Heat Exchanger: Although not using liquid to cool the CPUs directly, the hot air is cooled at the back of the rack rather than sent to the rest of the data center. The cool liquid is part of the rear door and heats up as the liquid flows downward. The warm or hot liquid must now be cooled as well.

Overall, with the increase in the Watts that are generated in each generation of CPUs and GPUs increasing, new methods to cool these chips will become more important as data centers are updated. Liquid has the ability to cool much hotter chips than air does, which reduces operating expenses and can keep CPUs and GPUs running at their maximum performance.

Supermicro manufactures a broad range of servers that can accommodate the latest and most powerful CPUs and GPUs available today. Supermicro servers are used in a wide variety of industries worldwide. Several installations are using various liquid cooling technologies to save costs and increase performance.


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