Nvidia staffer called Microsoft’s cooling system for Blackwell GPUs ‘wasteful,’ internal email shows

As Nvidia works to install some of its newest chips in Microsoft data centers, an employee at the GPU giant observed in early fall that Microsoft’s cooling approach at one facility seemed “wasteful.”

Nvidia has been deploying its GB200 Blackwell architecture at Microsoft and other tech giants as demand for compute to train and run AI models surges.

Blackwell, announced in March 2024, is roughly twice as powerful as its predecessor, Hopper, Nvidia CEO Jensen Huang said at launch. GB200 is part of an earlier wave of Blackwell deployments, with the GB300 generation now available.

In early fall, an internal email sent by a staffer on the Nvidia Infrastructure Specialists (NVIS) team described one Blackwell installation of server racks for OpenAI, which Microsoft supports as its cloud partner and largest investor.

The email described the setup of two GB200 NVL72 racks, each of which houses 72 Nvidia GPUs. The setup uses liquid cooling technology, given the heat generated by multiple GPUs operating closely in tandem.

The staffer wrote that Microsoft’s “cooling system and data center cooling approach for their GB200 deployment seems wasteful due to the size and lack of facility water use, but does provide a lot of flexibility and fault tolerance,” according to the memo.

While liquid cooling is used for the servers, data centers also use a second, building-level system to expel heat from the facility,…