Lawrence Livermore NL Sierra is a large GPU cluster operated by US Department of Energy, located in the United States, in the public sector. It came online around June 2018. At that moment it ranked number 2 among known clusters.
It is built on 17,280 NVIDIA V100. That amounts to about 1.1K H100e of AI compute. The cluster draws roughly 11.5 MW. Its hardware is estimated at $137M.
Epoch AI rates the certainty of this record as confirmed.