You may have heard of the Top500, a list of the world’s fastest supercomputers. But there’s also the Green500, which ranks—you guessed it—the most energy-efficient supercomputers. Italy’s 3-petaflop Eurora supercomputer, installed this week at the Cineca facility in Bologna, has exceeded the energy efficiency of the top system on the Green500 by 26 percent, easily setting a new record via its use of warm-water cooling. Eurora measures out at 3,150 megaflops per watt, which tops the 2,499 megaflops per watt achieved by the current leader, the Beacon at the University of Tennessee. Available to members of the Partnership for Advanced Computing in Europe (PRACE) and major Italian research entities, Eurora was built for research across a range of scientific disciplines, including material science, astrophysics, life sciences and Earth sciences. Eurora is a prototype system developed for Cineca under the PRACE 2IP initiative, a European partnership for advanced computing, with the goal of providing an economical, environmentally sensitive (but robust) computing infrastructure. The Eurora supercomputer also serves as an endorsement for Eurotech, the manufacturer, and its Tigon architecture, which packs a pair of Xeon E5 chips per compute node. Each of Eurora’s 64 compute nodes includes 16 cores, with eight nodes connected via a 40 Gbps QDR Infiniband or 56 Gbps FDR Infiniband backplane. Up to 64 GB of memory is available to each node, along with either 1,024 GB of disk storage or a 256-GB solid-state disk. There’s also the option of either an Intel Xeon Phi coprocessor or an Nvidia Tesla GPU; with the Eurora, Eurotech opted for the latter. Each Tesla chip can access up to 12 GB of DDR5 memory, if the Eurora was built to the standard Tigon specifications. Each rack’s total compute power is 350 teraflops, and there are 320 Infiniband + 272 Gigabit Ethernet I/O connections. In total, 100 kW is routed to each rack. The key, however, is Eurotch’s Aurora system, which re-circulates water directly to the components, cooling the system much more directly and efficiently than air cooling via chillers. The inlet temperature of the water can also vary, with Eurotech claiming that the water can enter at an inlet water temperature of between 18°C to 52°C, with varying flow rates. The result is an eye-popping Power Usage Effectiveness of 1.05, Eurotech claims, one of the lowest on record. The water itself doesn’t have to be cooled; instead, the waste heat can be pumped out via the warm water and used for other purposes, such as heating other areas of the facility. Eurotech estimates that Cineca will save a whopping 2.5 million kilowatt-hours, or $500,000 in energy costs, while eliminating over 1,500 tons of CO2 emissions as compared to a typical CPU cluster of similar performance, Nvidia added in a blog post. “GPU accelerators are inherently more energy efficient than CPUs, and Tesla K20 accelerators widen this gap considerably,” Sumit Gupta, general manger of the Tesla accelerated computing business at Nvidia, wrote in a statement. “Energy efficiency has become the defining element of computing performance.” The system hasn’t been officially named to the top of the Green500 list, which parallels the TOP500 list of high-performance supercomputers with an eye toward power efficiency. Key to this, according to Wu Feng, the founder of the Green500, has been the introduction of coprocessors like the Xeon Phi and Tesla chips, which has generally raised the performance of the supercomputers on the list without raising power. However, power consumption is still on the rise, Wu said in November, when the latest edition of the Green500 list was released—and that’s still a concern. [caption id="attachment_7532" align="aligncenter" width="318"] Eurotch’s Aurora system re-circulates water directly to the components, cooling the system in an efficient manner.[/caption]   Image: Nvidia