Direct liquid cooling emerges as potential game-changer for supercomputing efficiency and thermal management.

Liquid cooling is making a comeback in data centers, returning to methods used in the mainframe era before air-cooled systems became the standard for general-purpose computing. According to Seguente Inc., a global energy and thermal management company that participated in a panel on theCUBE at SC24, direct liquid cooling is the future of energy-efficient data centers. This shift has been driven by the demands of AI infrastructure, making cooling technology one of the most important topics in AI server designs.

Seguente collaborates with server vendors such as Lenovo and Dell Technologies Inc., along with Nvidia Corp., to transform existing computing racks with more sustainable cooling mechanisms that support higher workloads. During an exclusive broadcast on theCUBE at SC24, representatives from the three companies—Raffaele Luca Amalfi, co-founder and chief executive officer of Seguente; Tim Shedd, engineering technologist at Dell Technologies Inc.; and Dion Harris, director of accelerated data center GTM at Nvidia Corp.—discussed the shift toward liquid cooling. Shedd explained that "Cooling is just a tool to enable energy-efficient computing," noting that with H100 servers, "we're deploying those 64 GPUs with a rear door heat exchanger. So, we liquid-cooled the rack while keeping water out of the chassis. It turns out that addressed a whole bunch of TCO energy efficiency and the ability to deploy very quickly to the customer."

Multiple direct-to-chip liquid cooling methodologies are being pursued, including warm water cooling (which Dell is pursuing in response to guidance from the Open Compute Project), phase change liquid cooling (a technology that Seguente champions, involving changing the state of a thermally conductive medium from liquid to gas and back), hybrid liquid/air solutions, and immersive cooling. New chips and systems from Nvidia are driving the need for these innovations. Harris explained that "Nvidia is no longer selling a GPU. We're really selling customers a data center. We're looking at lots of different innovative ways to give more performance out of that computing stack, out of that networking stack. And oftentimes it involves driving more compute density, which therefore requires different innovations, whether it be through liquid cooling, through the bus bars, through the entire infrastructure that supports the specific computing infrastructure."

Seguente emphasizes the sustainability benefits of its solutions, with Amalfi highlighting the company's Coldware technology, which can capture and dissipate heat while saving energy across the entire system. Dell's Shedd underscored the importance of capturing heat at high temperatures before it reaches data center aisles, explaining that the rear door solution will "capture the heat before it goes into the aisle of the data centers so that you can basically offload some of the energy consumption on the HVAC systems." With customers needing to retrofit existing data centers, both Shedd and Harris anticipate hybrid air and liquid cooling solutions will be prevalent as the industry transitions.

The architectural shift is reshaping data center design fundamentally. As Shedd noted, "Instead of hot aisles and cold aisles, we're talking about wet aisles and dry aisles now. We're going to be distributing liquid through in one aisle and feeding liquid to those racks and maybe to redo heat exchangers. What this does is kind of opens up space, it opens up the operating environment so that we're no longer constrained by all of the challenges of getting air to the racks."