High-performance computing (HPC) systems are chasing performance as businesses and research facilities search for powerful processors to keep pace with unrelenting data growth. While government and research labs have historically been the primary users of HPC systems, in recent years, the split between the public and private sector is almost exactly 50/50. In 2019, nearly half of HPC server system revenues, totaling $13.7 billion worldwide, came from the private sector. Markets spanning oil and gas, automotive, finance and healthcare rely heavily on HPC to support complicated business operations that enterprise server systems cannot handle. As HPC workloads become more complex, processors require denser configurations. These power-hungry applications rely on optimized cooling solutions to maximize power density and increase compute performance. With innovative, reliable, and efficient liquid cooling systems for HPC systems, businesses and research facilities can future-proof their data systems.
Tech Innovation vs. Sustainability: Can they co-exist?
HPC-reliant industries have one thing in common; they need to process dense datasets reliably and efficiently. This reliance is only going to strengthen as workloads grow. In preparation for this societal shift, Berkeley Lab introduced their next-generation exascale supercomputer, Perlmutter, in May 2021. The lab predicts this supercomputer will play a key role in advancing scientific research in microbiology, genetics, climate change, and material sciences. HPC is opening doors for scientific research and societal advancements. To fulfill its role, HPC systems must continuously advance and innovate to satisfy customer demands.
Despite the overflowing number of benefits worldwide, one common misconception is that technology improvements cannot exist alongside sustainable practices. However, sustainability and progress don’t have to be in direct competition with each other. It’s possible to prioritize and achieve both.
Innovative Cooling Techniques for High-Performance Computing
Let’s examine liquid cooling in high-performance computing to support the coexistence of technological advancements and sustainability.
HPC applications seek dense computing configurations to manage, store and process data. Unfortunately, these configurations result in very high amounts of dissipated heat, causing hot spots and thermal bottlenecks in servers. In many cases, a shift from air cooling to liquid cooling has occurred to facilitate the continued densification of HPC applications. This has resulted in water cooling techniques, such as CPU cold plates, to remove heat from the server processors, allowing them to maintain safe operating temperatures.
However, even though the typical mental image for HPC applications consists of server slices and in-rack cooling systems, oftentimes, sustainability benefits are realized by an efficient implementation of the facility cooling system. The facility cooling system’s function is to take the heated coolant emerging from servers and reject its heat into the surrounding ambient air to provide chilled water back to the servers continuously.
Chillers and Cooling Towers Contribute to Higher TCO
Common facility cooling techniques in conventional high-performance server cooling systems include cooling towers and chiller units. These technologies provide chilled water to the liquid-cooled servers, often in concert with coolant distribution units in the racks. Cooling towers and chiller units are great for high-density compute applications. They can chill the coolant below the ambient temperature and provide highly effective cooling to the high heat dissipation elements. However, these technologies often expend water and energy, as they rely on water-intensive evaporative cooling and energy-intensive compression cycles to lower the coolant temperature. As a result, these cooling systems seriously impact the data center cooling ROI with their operational costs.
Thermosyphons Reduce Energy and Water Expenditure in HPC Facilities
Another facility cooling technique gaining in popularity is the thermosyphon. A thermosyphon is a highly passive cooling technique that takes advantage of density differences and gravity to provide facility cooling of HPC liquid-cooled systems with minimal water and energy expenditure. This is a highly sustainable facility cooling technique for HPC applications. However, a significant downside is that it cannot reduce the temperature any lower than the surrounding ambient temperature, which makes maintaining server temperatures at safe levels challenging in high-density server racks, especially in hot climates.
Liquid Cooling for High-Performance Computing Applications
Innovative technologies are facilitating more frequent use of thermosyphons, and therefore more sustainable computing. Microconvective liquid cooling is a direct-to-chip cooling technique that offers very low thermal resistance operation. By lowering thermal resistance at the chip level, hot water cooling systems can be implemented, and thermosyphons can be used more frequently at the facility level for low energy, low water use operation. Microconvective heat sinks replace microchannel cold plates and heat pipes for server rack cooling to achieve highly sustainable HPC operation while still offering the highest density in compute applications. Facilities can leverage traditional pump cooling systems while future-proofing against lower case temperatures, even with warmer coolants.
Increase Rack Density, Improve Compute Performance, and Drive Sustainability Improvements
As demand for high-performance computing continues to rise, it’s evident that the environment and technology can benefit from each other as innovative solutions emerge on the market. As a result, green cooling is a viable and practical choice. With new technologies, innovators can bridge the gap between the environmental and technological divide, keeping up with compute-intensive demand while promoting a sustainable future.
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 Hyperion Research Team. (2020). 2019 Market Results, New Forecasts and HPC Trends: SC20 Virtual Market Update. Hyperion Research. https://hyperionresearch.com/wp-content/uploads/2020/11/SC20-HPC-Market-Update_11.17.20.pdf
 GCN Staff. (2021, June 1). Next-gen supercomputer lays foundation for exascale. GCN. https://gcn.com/articles/2021/06/01/perlmutter-supercomputer.aspx