Is Colossus the “Largest” AI Supercomputer in the World?

Posted on September 13, 2025 by JimS

By Jim Shimabukuro (assisted by Perplexity)
Editor

Introduction: Elon Musk’s Colossus—built by xAI in Memphis—is currently considered the largest AI supercomputer in the world in terms of GPU count, computing power, and rapid build-out, but it is not the largest data center globally when measured by physical size or total server capacity. Competitive megacenter projects from China, the U.S., and Europe rival or exceed it in site area and may soon overtake xAI both in scale and ambition.wikipedia+5

Image created by Copilot.

Current Global Leader: xAI Colossus

  • Located in Memphis, Tennessee, Colossus surpassed 200,000 GPUs in mid-2025, with power draw exceeding 250 MW and expansion moving toward a target of 1 million GPUs and up to 1.2 GW total power.nextbigfuture+2
  • Colossus leads in AI training capacity and raw GPU processing, deploying more H100, H200, and Blackwell chips than any competitor as of September 2025.nextbigfuture+2
  • The build-out for Colossus was completed in an exceptional 122 days, with aggressive expansion into additional Memphis sites.time+1

Global Competitors & Their Countries

  • China Telecom (Inner Mongolia Information Park, Hohhot, China):
    • Still the world’s largest by square footage (over 10.7 million sq. ft.), hosting 100,000+ servers and supporting rapid expansion for AI workloads.datacentremagazine+2
  • Switch Citadel Campus (Nevada, USA):
    • Among the largest colocation sites globally with 7.7 million sq. ft. and advanced green power deployments, but not matched to Colossus in AI-specific processing.gbc-engineers+1
  • OpenAI/Microsoft:
    • Recently built a Texas facility with capacity for 300 MW and plans to hit 1 GW in 2026, with a similar ambition to xAI regarding dedicated AI infrastructure.tomshardware+1
  • Meta, Google, Oracle:
    • Building AI megacenters in the U.S., with 100,000+ GPU deployments and aggressive expansion, but trailing Colossus in absolute count as of mid-2025.visualcapitalist+1
  • Czech Operator CRA (Prague region, Czech Republic):
    • Began constructing Eastern Europe’s largest data center in September 2025, intended to close the gap with top U.S. and Asian facilities in three years.datacenterknowledge
  • Pelagos Data Centres (Gibraltar, UK):
    • Announced £1.8 billion investment for a major new trans-European hub expected to be operational by 2033.dataxconnect

Timelines and Ambition

  • OpenAI’s Texas project and China Telecom’s data centers could overtake Colossus in physical scale, power, or AI compute as soon as late 2026, given project schedules and announced expansions.brightlio+2
  • Meta and Oracle have announced multi-year build-outs aiming to surpass 200,000 GPUs, with Google also targeting gigawatt-class builds, but Colossus remains uniquely focused on AI.nextbigfuture+1
  • European and Asian expansions, especially in China’s Inner Mongolia and upcoming UK/Gibraltar facilities, may overtake Colossus in overall infrastructure, aided by state-led incentives.brightlio+2

Comparative Ambition

  • Chinese and U.S. rivals are matching or exceeding Colossus in total site size, although no AI-specific computer yet matches Colossus’s planned 1 million GPU target.euronews+1
  • OpenAI/Microsoft’s Texas supercenter and China Telecom aim for higher total computing power or square footage, often with broader cloud or telecom applications beyond AI.tomshardware+1
  • European projects (CRA, Pelagos) are catching up, but are less ambitious in AI density or specialized supercomputing at present.datacenterknowledge+1

Table: Data Center Leaders (2025)

Data CenterCountryMetric Where LargestPlanned Overtake DateArea/Compute Ambition
xAI Colossus (Memphis)USALargest AI supercomputer—1M GPUs, 1.2 GW by 2026nextbigfuture+1
China TelecomChinaLargest sq. footage2026+10.7M+ sq. ft., expandingbrightlio+1
Switch Citadel (Nevada)USALargest colocation facility—7.7M sq. ft., 100+ MWdatacentremagazine
OpenAI/Microsoft (Texas)USAAI capacity contenderLate 20261 GW planned, 300 MW by 2025tomshardware
CRA/PragueCzechiaLargest regional expansion2027EU-scale, under constructiondatacenterknowledge
Pelagos (Gibraltar)UKLong-term EU megacenter2033£1.8B investmentdataxconnect

Colossus is currently the most ambitious AI-specific data center, but could be overtaken as early as 2026 in size, computing power, or innovation by OpenAI/Microsoft, China’s telecom giants, and newly announced megacampus builds in the U.S., Europe, and Asia.gbc-engineers+4

  1. https://fortune.com/2025/03/14/super-micro-ceo-charles-liang-elon-musk-xai-grok-nvidia-server-chips/
  2. https://en.wikipedia.org/wiki/Colossus_(supercomputer)
  3. https://www.datacenterfrontier.com/machine-learning/article/55244139/the-colossus-ai-supercomputer-elon-musks-drive-toward-data-center-ai-technology-domination
  4. https://datacentremagazine.com/top10/top-10-biggest-data-centres
  5. https://brightlio.com/largest-data-centers-in-the-world/
  6. https://gbc-engineers.com/news/largest-data-center-in-the-world
  7. https://time.com/collections/time100-ai-2025/7305842/elon-musk-ai/
  8. https://www.nextbigfuture.com/2025/08/xai-google-openai-and-meta-race-to-gigawatts-of-ai-data-centers.html
  9. https://www.nextbigfuture.com/2025/02/building-the-1-2-gigawatt-xai-data-center-in-2025.html
  10. https://www.visualcapitalist.com/the-worlds-most-powerful-ai-supercomputers/
  11. https://nvidianews.nvidia.com/news/spectrum-x-ethernet-networking-xai-colossus
  12. https://www.tomshardware.com/tech-industry/artificial-intelligence/openais-gargantuan-data-center-is-even-bigger-than-elon-musks-xai-colossus-worlds-largest-300-mw-ai-data-center-in-texas-could-reach-record-1-gigawatt-scale-by-next-year
  13. https://www.datacenterknowledge.com/data-center-construction/new-data-center-developments-september-2025
  14. https://dataxconnect.com/data-centre-news-5th-september-2025/\
  15. https://www.euronews.com/next/2024/12/05/elon-musks-xai-plans-expansion-of-ai-supercomputer-colossus
  16. https://thenetworkinstallers.com/blog/elon-musk-data-center-statistics/
  17. https://www.xyzreality.com/resources/2025-data-center-trends
  18. https://etcjournal.com/2025/08/15/elon-musks-colossus-the-gambit-that-could-reshape-ai-forever/
  19. https://www.cnn.com/2025/05/19/climate/xai-musk-memphis-turbines-pollution
  20. https://www.nbcnews.com/news/us-news/musk-xai-colossus-supercomputer-boxtown-memphis-tennessee-rcna206242

Expansion Timeline for Colossus

Elon Musk’s Colossus data center in Memphis began as the world’s largest AI supercomputer in mid-2024 and has rapidly expanded both in GPU count and physical footprint through multiple publicly announced phases.wikipedia+3

  • March 2024: Memphis site (former Electrolux factory, 785,000 sq ft) selected.datacenterfrontier+1
  • June 2024: Official project announcement; rapid buildout begins with city, state, and utility support.wikipedia+1
  • September 2024: Colossus launches operation with 100,000 Nvidia H100 GPUs, hitting global #1 for AI supercomputing.nvidianews.nvidia+2
  • October–December 2024: Capacity doubles to 200,000 H100/H200 GPUs and power to ~250 MW, enabled by temporary gas turbines and Tesla Megapacks while local utilities boost infrastructure.teslarati+3
  • December 2024: Announcement of major property expansion; plans for up to 1 million GPUs and a dedicated water recycling plant receive city approval.memphischamber+2
  • March 2025: xAI acquires an additional 1,000,000 sq ft site in Memphis’ Whitehaven area for future buildout.wikipedia
  • Summer 2025: Second-phase initiative underway, including bringing 110,000 GB200 GPUs online and expansion of physical facility footprint.voice.lapaas+1
  • July 2025: Colossus 2 announced, targeting over 550,000 Blackwell GB200/GB300 chips on site (eventually scaling to 1 million+ GPUs), with the gigawatt-scale plant to be partially online by 2026.mlq+1

Current GPU Count (as of September 2025)

  • Operational:
    • 150,000 H100 GPUs
    • 50,000 H200 GPUs
    • 30,000 GB200 GPUs
  • Imminent Expansion:
    • 110,000 GB200 GPUs coming online at a second Memphis facility
  • Total (active/online):
    • Approx. 230,000—250,000 GPUs in service, with rapid growth toward the 1 million GPU mark expected by late 2026.visualcapitalist+2

Colossus remains the most ambitious AI-specific cluster, rapidly adding capacity and with expansion infrastructure in place for a projected 1 million+ GPUs and 1.2 GW power target by 2026.nextbigfuture+2

  1. https://en.wikipedia.org/wiki/Colossus_(supercomputer)
  2. https://www.datacenterfrontier.com/machine-learning/article/55244139/the-colossus-ai-supercomputer-elon-musks-drive-toward-data-center-ai-technology-domination
  3. https://www.teslarati.com/xai-supercomputer-memphis-upgraded-1-million-gpus/
  4. https://www.nextbigfuture.com/2025/02/building-the-1-2-gigawatt-xai-data-center-in-2025.html
  5. https://nvidianews.nvidia.com/news/spectrum-x-ethernet-networking-xai-colossus
  6. https://memphischamber.com/blog/press-release/expansion-follows-december-announcement-of-supercomputer-growth-and-tech-partnership-ecosystem/
  7. https://voice.lapaas.com/xai-colossus-2-supercomputer-preview/
  8. https://mlq.ai/news/xai-seeks-12-billion-funding-for-colossus-2-supercluster-unveils-deployment-timeline/
  9. https://www.visualcapitalist.com/the-worlds-most-powerful-ai-supercomputers/
  10. https://www.nextbigfuture.com/2025/03/construction-power-timeline-for-xai-to-reach-a-3-million-gpu-supercluster.html
  11. https://www.grokmountain.com/p/origin-of-grok-3-the-colossus-data
  12. https://builtin.com/artificial-intelligence/xai-supercomputer-colossus
  13. https://www.areadevelopment.com/data-centers/q4-2024/the-colossus-of-memphis-elon-musks-supercomputing-investment-transforms-the-region.shtml
  14. https://teamsilverback.com/ai-milestone-achieved-at-musks-new-memphis-data-center/
  15. https://www.rdworldonline.com/how-xai-turned-a-factory-shell-into-an-ai-colossus-to-power-grok-3-and-beyond/
  16. https://convergedigest.com/xai-plans-major-expansion-of-colossus-supercomputer-in-memphis/
  17. https://www.forbes.com/sites/johnwerner/2024/11/14/three-big-things-to-know-about-xais-colossus-this-week/
  18. https://etcjournal.com/2025/08/15/elon-musks-colossus-the-gambit-that-could-reshape-ai-forever/
  19. https://epoch.ai/data-insights/ai-supercomputers-cost-trend
  20. https://www.datacenterdynamics.com/en/analysis/nvidia-wins-intel-loses-and-xai-becomes-a-colossus-a-year-in-compute/

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