Hot-water cooled supercomputer goes live

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IBM has delivered a first-of-a-kind hot water-cooled supercomputer to the Swiss Federal Institute of Technology Zurich (ETH Zurich), marking a new era in energy-aware computing. The innovative system, dubbed Aquasar, consumes up to 40% less energy than a comparable air-cooled machine. Through the direct use of waste heat to provide warmth to university buildings, Aquasar's carbon footprint is reduced by up to 85%.

Building energy efficient computing systems and data centers is a staggering undertaking. In fact, up to 50% of an average air-cooled data center's energy consumption and carbon footprint today is not caused by computing, but by powering the necessary cooling systems to keep the processors from overheating – a situation that is far from optimal when looking at energy efficiency from a holistic perspective.

Watch the video on the Aquasar system

The development of Aquasar began one year ago as part of IBM's First-Of-A-Kind (FOAK) program, which engages IBM scientists with clients to explore and pilot emerging technologies that address business problems. The supercomputer consists of special water-cooled IBM BladeCenter Servers, which were designed and manufactured by IBM scientists in Zurich and Boblingen, Germany. For direct comparison with traditional systems, Aquasar also holds additional air-cooled IBM BladeCenter servers. In total, the system achieves a performance of six Teraflops and has an energy efficiency of about 450 megaflops per watt. In addition, 9 kW of thermal power are fed into the ETH Zurich's building heating system. With its innovative water-cooling system and direct utilization of waste heat, Aquasar is now fully-operational at the Department of Mechanical and Process Engineering at ETH Zurich. 

The processors and numerous other components in the new high performance computer are cooled with up to 60 C warm water. This is made possible by an innovative cooling system that comprises micro-channel liquid coolers, which are attached directly to the processors, where most heat is generated. With this chip-level cooling, the thermal resistance between the processor and the water is reduced to the extent that even cooling water temperatures of up to 60 C ensure that the operating temperatures of the processors remain well below the maximally allowed 85 C. The high input temperature of the coolant results in an even higher-grade heat at the output, which in this case is up to 65 C.

Overall, water removes heat 4,000 times more efficiently than air. Aquasar is part of a three-year collaborative research program called "Direct use of waste heat from liquid-cooled supercomputers: the path to energy saving, emission-high performance computers and data centers." In addition to ETH Zurich and IBM Research - Zurich, the project also involves ETH Lausanne. It is supported by the Swiss Centre of Competence of support for Energy and Mobility (CCEM).