HPE Cray EX cabinet

The physical unit the US exascale systems are actually counted in: Frontier, El Capitan and Aurora are all built from this cabinet, and a system's cabinet count is frequently the first number published about it, before FLOPS. Every blade in it takes liquid at the connector, so there is no air-cooled fallback tier the way there was in the direct-to-chip cold-plate designs that preceded it. That is a single point of commitment: the cabinet has no configuration in which it runs without a facility water loop already in place, which means the building has to be ready before the compute can arrive.