Computer History Museum, Timeline of Computer History: Linux-based Supercomputing (1998)

The first supercomputer using the Linux operating system, consumer, off-the shelf parts, and a high-speed, low-latency interconnection network, was developed by David A. Bader while at the University of New Mexico. From this successful prototype design, Bader led the development of “RoadRunner”, the first Linux supercomputer for open use by the national science and engineering community via the National Science Foundation’s National Technology Grid. RoadRunner was put into production use in April 1999. Within a decade this design became the predominant architecture for all major supercomputers in the world.

https://www.computerhistory.org/timeline/1998/