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energy efficiency in HPC

liquid form,’ according to Barrington. Keeping the circuit totally immersed in a

liquid avoids the problem of thermal shocking that can arise in the traditional cooling paradigm as cold air is blown over hot processors. ‘By immersing the motherboard into Novec we are looking to maintain a constant temperature and present the heat to the outside casing efficiently and this reduces the server energy load by 20 per cent as you have no fans,’ he continued. ‘We also provide a cabinet with a separate sealed water system and, using CFD, we are trickling the water using gravity to a heat exchanger at the bottom of the cabinet.’ Te heat is then available to be reused as office heating or to be rejected to the environment via passive cooling. Te final beta systems, which are fitted out

with lots of sensors, are at academic facilities for final testing. Iceotope will be starting shipments to customers from the beginning of September. Barrington expects that the system will cut the overall energy bill in half, but he adds that there are also savings in infrastructure costs ‘so you can buy more compute for the same budget’.

Bathing in oil Christiaan Best, CEO of Texas-based Green Revolution Cooling, also stressed the important of the cooling infrastructure. ‘If you think about

it, you have a lot of really smart people designing computers and motherboards and local contractors doing the cooling system. It’s quite a juxtaposition when you have them both in the same room.’ He noted that studies have found that 45 per cent of the cost of a data centre has nothing to do with the computing and believes that there has been ‘a race to the bottom’ on the infrastructure side. Whoever can build the cheapest gets the contract – but, he added: ‘Te technology is unchanged for 50 years and that

submerges the entire server in liquid: ‘It’s quite literally: take your server out of the cardboard box, replace the thermal paste between the CPU and the heatsink with a foil. Remove the fans. Remove the spindle-type hard drives. And dump it right in.’ In some cases, he noted, foil rather than thermal paste is already in use, eliminating that step. Te system also necessitates the use of solid state memory. Te working fluid is also different: ‘It’s safe to call it baby oil – it’s very, very close but doesn’t


can’t be sustained. Tere is so much going on, on the computing side; and there is so little going on, on the other side. It’s a question of not if, but when people switch to liquid cooling’. He too has the larger goal of finding a way to recapture that heat, citing one installation in Sweden where the plan is to repurpose the ‘waste’ heat to provide heating for the building – ‘it is all being repurposed. Tat’s the future.’ In contrast to the modular approach adopted by Iceotope, Green Revolution Cooling


Green high-performance computing

Green computing with GPUs Steve Scott, Nvidia’s Tesla Business Unit

New advances in power and cooling technology Bill Mannel, SGI

Energy efficiency and supercomputing Dona L. Crawford, Lawrence Livermore National Laboratory

What does the year ahead hold for the HPC market? Industry experts share their predictions

JUNE/JULY 2012 31 Sponsored by

have the same fragrances. If it’s good enough for your child, it’s good enough for your computer.’ Te fluid has to be pumped round – it is forced convection. Similar oil-based systems have been used in power electronics for many years, he said, and its dielectric strength is better than air. ‘Removing heat can be done in many ways – you can pump it into your district heating. In Texas, you pump it into warm to hot water and have an evaporative cooler’. Green Revolution Cooling shipped its first

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