Immersion Cooling: Dunking Computers to Keep Them Cool

Electronics and fluids don’t generally mix. But teams from different corners of the globe are showing that immersing data-center gear in specialized fluids could be the best way to keep them cool.

Computers may fail if they get too hot, so they often use power-hungry
fans to cool them down. Recently engineers have deployed ways to cool supercomputers by circulating water in pipes near processors. Fluids are far more dense than air, which makes them more efficient at drawing heat away from computers. This efficiency is increasingly important—a 2023 study finds that the energy required to keep the servers in data centers from overheating represents 30 to 40 percent of the total energy that data centers consume.

However, water cooling faces problems of its own. The water carrying heat from computers is typically piped to cooling towers. There its heat converts a separate supply of water into mist that evaporates into the atmosphere. In 2022,
Google’s data centers consumed about 19 billion liters of freshwater for cooling.

Sandia researchers are testing out cooling computers by submerging them entirely in non-conductive oil.

Now, two separate results are putting a different technology on the map—immersion cooling, or dunking whole data centers in oil. The oil is non-conductive and non-corrosive, so that it can be in direct contact with electronics without short-circuiting or damaging them. The technology holds the potential to cut energy usage in half, says Oliver Curtis, co-CEO of immersion-cooled data center company
Sustainable Metal Cloud.

“We’ve proven that you can get the same amount of performance, but for half the amount of energy, and if you can do that, it’s our social responsibility to proliferate this technology,” Curtis says.

Dunking an AI Factory

Yesterday, the
MLPerf AI training competition announced a new benchmark—energy consumption. As the name suggests, it measures the power each submitting machine consumes when performing each of its other benchmarks, such as training a large language model or a recommendation engine. This new category only had one submitting organization, Singapore-based Sustainable Metal Cloud (SMC).

SMC was looking to show off its efficiency gains due its immersion-based cooling system. The system’s fluid is an oil called polyalphaolefin, which is a commonly used automotive lubricant. The oil is forced slowly through the dunked servers, allowing for efficient heat transfer.

The SMC team has figured out what modifications need to be made to servers to make them compatible with this cooling method over the long-term. Beyond removing the built-in fans, they switch out thermal interface materials that connect chips to their heatsinks, as some of those materials degrade in the oil. Curtis says the modifications they make are small but important to the functioning of their setup.

“What we’ve done there is…