Summit and Sierra supercomputer cooling solutions

Achieving optimal data center cooling efficiency requires effective water cooling of high-heat-density components, coupled with optimal warmer water temperatures and the correct order of water preheating from any air-cooled components. The Summit and Sierra supercomputers implemented efficient cooling by using high-performance cold plates to directly water-cool all central processing units (CPUs) and graphics processing units (GPUs) processors with warm inlet water. Cost performance was maximized by directly air-cooling the 10% to 15% of the compute drawer heat load generated by the lowest heat density components. For the Summit system, a rear-door heat exchanger allowed zero net heat load to air; the overall system efficiency was optimized by using the preheated water from the heat exchanger as an input to cool the higher power CPUs and GPUs.