Fairwater

Microsoft unveiled a datacenter design called Fairwater in September 2025¹ which built on a talk that Scott Guthrie gave at Build 2025.² The first Fairwater is in Wisconsin, though a second and third are also being built in Georgia and Wisconsin.³

AI factory design

Each Fairwater site follows a similar blueprint and has three major components: GPU, non-GPU, and cooling.

GPU system

The GPU system is housed in the large, two-story building in the center of the above photo¹ and contains “hundreds of thousands of interconnected NVIDIA GB200 GPUs”² which are operated as a “single, coherent cluster.”⁴

Network

The building uses two stories of GPUs and through-floor networking to allow more GPUs to fit into the transceiver limits of the high-speed interconnect.⁴ This interconnect uses a two-level tree based on 800G Ethernet that uses the MRC protocol.⁴

The only way in which over 100,000 GPUs can be assembled into a two-level tree using existing 64-port 800G switches is through lane splitting to increase switch radix. The blocking factor for Fairwater was not disclosed, but splitting each 800G port into 8x100G ports would allow up to 131,072 GPUs to be connected in a non-blocking fashion. Such port splitting aligns with Microsoft’s choice to use a protocol that supports packet spraying. It is also probably safe to assume that, like all AI supercomputers, the fabric uses a multi-plane tree.

Racks

Racks are standard GB200 NVL72 racks, each rated for 140 kW and arranged into 1360 kW rows.⁴

Storage and non-GPU

Storage and non-GPU compute systems are housed in a separate, air-cooled building to the side of the GPU datacenter. This building contains “exabytes of storage and literally millions of CPU compute cores”² which are used for data processing around AI training.¹

The Fairwater-Wisconsin site deploys this in a long, single-story building:¹

Cooling

The water cooling facility is the third major building and is comprised of a large building and two “fins” which support the closed-loop dry coolers.¹ “Over 90%” of the facility uses dry cooling, while the remaining 10% use outside air and evaporative cooling.

Fairwater Wisconsin

The Wisconsin site is 315 acres with a total of 1.2 million square feet of floor space, and it was built with “46.6 miles of deep foundation piles, 26.5 million pounds of structural steel, 120 miles of medium-voltage underground cable and 72.6 miles of mechanical piping.”¹ It will begin production in 2026.⁵

Site power

Photos of Fairwater suggest it is the $3.3 billion, 450 MW AI datacenter that Microsoft was building in Mount Pleasant, WI.⁶.

This facility is tied to a PPA that Microsoft signed with National Grid Renewables for 250 MW of solar generation.⁵⁷

History

Here’s a photo of the facility while it was still under construction in early 2025:²

Fairwater Georgia

The Fairwater Georgia site was disclosed on November 12, 2025⁴ and appears to be west of Fayetteville near Trilith Studios. It is fed by a 230 kV transmission line that is most closely interconnected with coal and gas-fired power stations.⁸

Footnotes

1. Inside the world’s most powerful AI datacenter ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

2. Scott Guthrie’s keynote at Microsoft Build 2025 - Unpacking the tech ↩ ↩² ↩³ ↩⁴

3. Inside Microsoft’s Plans for the ‘Most Advanced AI Data Center in the World’ ↩

4. Infinite scale: The architecture behind the Azure AI superfactory ↩ ↩² ↩³ ↩⁴ ↩⁵

5. https://www.cnbc.com/2025/09/18/microsoft-wisconsin-data-center.html ↩ ↩²

6. Microsoft data center will be the state’s largest electricity user. Power needs equal 300,000 homes ↩

7. https://www.datacenterdynamics.com/en/news/microsoft-signs-solar-ppa-with-national-grid-renewables-in-wisconsin/ ↩

8. https://openinframap.org/#15.03/33.45101/-84.51716 ↩