EuroHPC LUMI is a large GPU cluster operated by EuroHPC JU, located in Finland, in the public sector. It came online around September 2022. At that moment it ranked number 8 among known clusters.
It is built on 11,912 AMD Radeon Instinct MI250X. That amounts to about 2.3K H100e of AI compute. The cluster draws roughly 12.09 MW. Its hardware is estimated at $171M.
Epoch AI rates the certainty of this record as confirmed. Came online in phases, so unclear exactly when it became operational. A portion of it first was innagurated as operational June 2022, and close to 10k GPUs were confirmed to operational by Nov 2022. Reports suggest that "phase two" began in August. Marking the operational date as September as an estimate