Parallel linked CPUs. View several computer processing units (CPU's, blue blocks) linked in parallel. These units are housed in the computer room at the particle physics laboratory, Fermilab (Fermi National Accelerator Laboratory) near Chicago, USA. Each of the units contain a powerful R10000 chip. They are the main processing units of the Challenge XL computer. Up to 36 processing units are linked in parallel to one Challenge XL computer. The combined power of these units allows the computer to deal with the three dimensional geometric calculations necessary in particle physics. The Challenge XL is manufactured by the Silicongraphics computer company.