In his second report from the International Supercomputing Conference (ISC’14) which took place in Leipzig at the end of June, Tom Wilkie discusses different approaches to energy efficiency in high performance computing.

A casual observer at this year’s International Supercomputing Conference (ISC’14), held in Leipzig at the end of June, could be forgiven for thinking that the most popular engineering discipline in high-performance computing (HPC) today is a throwback to Victorian times – plumbing. Liquid cooling of supercomputers has finally come of age, with more than 21 of the exhibition stands at ISC’14 featuring liquid cooling in some form or other.

But, as Jean-Pierre Panziera, Chief Technology Director of Extreme Computing for Bull, pointed out, this is anything but Victorian technology. Bull is using its own supercomputers to work out the complex computational fluid dynamics involved in designing an efficient system, he said. In the search for energy efficiency, Bull is already looking beyond what Panziera referred to as ‘passive options’, such as cooling, to the more active approach of monitoring the energy usage of its servers and components and optimising the way in which the computation proceeds so as to be more energy efficient.

HP also announced its entry in the liquid cooling stakes at ISC’14, with a theatrical unveiling of a new liquid cooled system, the Apollo 8000, on its stand. This too uses warm water, although the heat is conducted from the components by hot plates and heat pipes to be removed by the water cooling at the edge of the board. HP claims the design has advantages in terms of ‘dry disconnect’. It is also hedging its bets, in that part of the newly announced Apollo series, the 6000, is a more traditional, air-cooled version.

But alcohol rather than water generated a lot of interest on the show floor, with a highly ingenious two-phase approach being pioneered by the Belgian company Calyos. By combining a two-phase latent heat effect with a passive capillary pump, the Calyos system allows the heat to be removed from the components without any need for external energy to pump the fluid round. (Read more)