America’s nuclear stockpile of weapons is aging, yet they must be certified as effective without physical testing. That is the challenge of the Department of Energy’s National Nuclear Security Administration (NNSA). Without underground testing, scientists must test, validate, and certify the nuclear stockpile using a combination of focused above-ground experiments, computational science and ...simulations that run on large computing clusters. The Commodity Technology System 1 (CTS-1) deployment has over 15 Penguin Computing, Inc. supercomputer clusters consisting of 83 Tundra* Scalable Units (SU). These clusters incorporate Intel® Xeon® processors and many other Intel® technologies, and Asetek* DCLC direct chip cooling technologies. All clusters began deployment at the NNSA’s tri-labs in early 2016, providing the computational power for scientists to carry out their missions. At the center of these powerful clusters is Intel® Omni-Path Architecture (Intel® OPA) connecting the large numbers of nodes together. This paper looks at the need for these systems and why Intel® OPA was chosen as a foundational component.