Microsoft Azure Meta AI Rental is a large GPU cluster operated by Microsoft, located in the United States, in the private sector. It came online around May 2022. At that moment it ranked number 10 among known clusters.
It is built on 5,400 NVIDIA A100. That amounts to about 1.7K H100e of AI compute. The cluster draws roughly 4.6 MW. Its hardware is estimated at $122M.
Epoch AI rates the certainty of this record as confirmed. Not marked "possible duplicate" since we don't have any other Microsoft supercomputers existing at this time that are this large and aren't known to be used by anyone else (eg, the 25k A100 supercomputer used by OpenAI)