https://www.theregister.co.uk/2018/06/18/hpe_astra_largest_arm_supercomputer/

HPE is building the world's largest Arm-based supercomputer, Astra – 2.5 petaFLOPS from 2,592 HPE Apollo 70s – for Sandia National Labs in the US, where it will run advanced modeling and simulation workloads in areas including national security and energy.

Apollo 70s have four compute nodes in a 2U case. The CPUs are Cavium Arm v8-A 64-bit Thunder X2 with up to 32 cores and 8 x DDR4 channels.