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xAI brings Colossus 2 supercomputer online in Memphis

xAI brings Colossus 2 supercomputer online in Memphis

New Capabilities

Second Memphis cluster roughly doubles training compute for Grok

Yesterday: Colossus 2 brought online

Overview

Updated Yesterday

xAI powered up Colossus 2, its second Memphis supercomputer, on October 9. The machine roughly doubles the training compute available for Grok, xAI's family of AI models, and gives the company one of the largest dedicated compute clusters on the planet.

The expansion is part of a broader race: at the frontier of AI, whoever can assemble the most capable clusters, power them reliably, and keep them running tends to lead on model quality. Colossus 2 is scheduled to grow to 1.21 million Nvidia GPUs by the end of 2026, fed by a dedicated 1.2-gigawatt gas power plant in nearby Southaven, Mississippi.

Why it matters

If Colossus 2 hits its targets, xAI gains the compute to train frontier-scale models like Grok 5, shifting the AI competitive balance.

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Key Indicators

1.44M
Combined GPU target
Colossus 1 and 2 combined if all expansion tranches land by end of 2026.
1.2 GW
Dedicated power plant capacity
41-turbine gas plant in Southaven, Mississippi, permitted in March 2026.
440,000
GB300 GPUs in use
In use at Colossus 2 as of late September 2026.
660,000
Additional GPUs expected
Scheduled to come online by end of 2026 in three tranches.
122 days
Colossus 1 build time
Time to stand up the first 100,000 H100 GPUs in 2024.

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People Involved

Organizations Involved

Timeline

February 2025 October 2026

11 events Latest: Yesterday Showing 8 of 11
Tap a bar to jump to that date
  1. Colossus 2 brought online

    Latest Milestone

    xAI brings Colossus 2 online, roughly doubling training compute for Grok.

  2. 440,000 GB300 GPUs in use

    Milestone

    440,000 GB300 GPUs in use at Colossus 2, with 660,000 more expected by year-end.

  3. Google rents GPUs from SpaceX

    Deal

    Google agrees to rent about 110,000 GPUs from SpaceX for $920 million monthly.

  4. Anthropic rents Colossus 1 capacity

    Deal

    Anthropic agrees to rent essentially all compute capacity at Colossus 1.

  5. Gas plant permit approved

    Regulatory

    Mississippi regulators permit 41-turbine, 1.2-gigawatt gas plant for the site.

  6. Musk declares Colossus 2 operational

    Statement

    Elon Musk says Colossus 2 is operational, with 1.5 gigawatts planned for April.

  7. First GPU cluster comes online

    Milestone

    About 110,000 Nvidia GB200 processors come online after a reported 91-day build.

  8. Cooling infrastructure installed

    Construction

    119 air-cooled chillers on site, roughly 200 megawatts of cooling capacity.

  9. xAI buys Memphis warehouse site

    Acquisition

    xAI affiliate purchases warehouse at 5420 Tulane Road for about $80 million.

Scenarios

1

Colossus 2 hits 1.21 million GPUs by year-end

Possible Resolves by Jan 15, 2027

Discussed by: xAI's roadmap, reported by AIReport.NET and Compute Atlas

xAI has scheduled three tranches of about 220,000 GB300 GPUs each, landing by end of October, November, and December. If all land on time, Colossus 2 alone would hold about 1.21 million chips, and the combined fleet including Colossus 1 would reach about 1.44 million.

2

Expansion falls short as chip deliveries slip

Possible Resolves by Jan 15, 2027

Discussed by: Skeptics cited by AIReport.NET

Chip deliveries slip, transformers and switchgear are back-ordered, and power projects face permitting delays. The 1.44 million figure is best read as a ceiling rather than a promise.

3

Environmental lawsuit reshapes the buildout

Uncertain Resolves by Jul 1, 2027

Discussed by: NAACP, Southern Environmental Law Center, Earthjustice

The federal lawsuit over unpermitted turbines in Southaven could force changes to how xAI powers the cluster. The Justice Department moved to dismiss the case in June 2026, arguing national security interests, but the case remains pending.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

December 1943 - June 1944

Colossus (1943-1944)

British engineers at Bletchley Park built the world's first programmable electronic computer in under a year. Named Colossus, it was designed to break the Lorenz cipher used by German high command, processing 5,000 characters per second.

Then

Colossus helped break German military communications, contributing to Allied victories including D-Day.

Now

It established the template for electronic computing, though its existence remained secret until the 1970s.

Why this matters now

The name is the same, and so is the pattern: a machine built in months, at unprecedented speed, to gain a decisive advantage. xAI's Colossus 2 follows that playbook in the AI race.

June 1942 - August 1945

Manhattan Project (1942-1945)

The U.S. government compressed a multi-year research program into three years, building massive industrial facilities at Oak Ridge, Tennessee and Hanford, Washington. The project employed 130,000 people and cost about $2 billion, roughly $30 billion in today's dollars.

Then

The project produced the first atomic weapons, used at Hiroshima and Nagasaki in August 1945.

Now

It established the model for large-scale, time-compressed government and industrial projects.

Why this matters now

Like the Manhattan Project, Colossus 2 compresses timelines and builds massive industrial infrastructure in a single region. The speed of construction and its local impacts are central to both stories.

Sources

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