Colossus (supercomputer)

Colossus is a supercomputer developed by xAI, an artificial intelligence (AI) company founded by Elon Musk. Construction on Colossus began in 2024 in Memphis, Tennessee, and is continuing to expand today. It is currently believed to be the world's largest AI supercomputer. Its purpose is to train the company's AI language model, Grok, and also train the social media service X. It also supports operations for Musk's other companies, such as SpaceX.

Background

Colossus was launched in September 2024 at a former Electrolux site in South Memphis to train the AI language model Grok. Reportedly, within 19 days of the project's conception, xAI was ready to begin construction. In comparison, other data centers have taken an average of four years to finalize the plans for a project, ship the equipment, and have it installed.

The site was chosen because the abandoned Electrolux building could be repurposed to expedite construction. Another advantage of the site was proximity to a nearby wastewater treatment facility providing a water source. As of February 2025 xAI plans to build an $80 million facility to process additional wastewater for use at the supercomputer.

xAI

Musk incorporated xAI in March 2023 with the stated purpose of understanding the "nature of the universe". The team includes former members of OpenAI, DeepMind, Microsoft, and Tesla. Musk has a history of involvement in artificial intelligence; he was one of the founding members of the company OpenAI, investing up to $45 million USD in 2015. He left OpenAI in 2018, reportedly to avoid conflicts of interest with his own company, Tesla. However, it has also been reported that he had made a bid for leadership at OpenAI and left when his proposal was rejected. The exact reasons for his departure with the company remain unclear.

Both Dell Technologies and Supermicro partnered with xAI to build the supercomputer. It was originally powered by 100,000 Graphic Processing Units (GPUs) and was constructed in 122 days. The chips were supplied primarily by the tech company Nvidia, which currently manufactures some of the most powerful processing chips on the market. Each GPU is housed within one of Supermicro's 4U Universal GPU Liquid Cooling Systems to prevent overheating. Ninety-two days after the first 100,000 GPUs were built, xAI announced that they had increased the system to 200,000 GPUs and that they intended to continue increasing the computer's processing power to 1 million GPUs. Colossus is currently the largest AI training platform in the world.

Grok

Grok, xAI's AI language model powered by Colossus, is intended to be "...your truth-seeking AI companion for unfiltered answers with advanced capabilities in reasoning, coding, and visual processing". The chatbot is heavily inspired by science fiction; the name Grok derives from a term coined by author Robert A. Heinlein in his 1961 novel ''Stranger in a Strange Land'' to describe the ability "...to understand intuitively or by empathy, to establish rapport with..." and it is modeled after the irreverent and dry humor of The Hitchhiker's Guide to the Galaxy. Grok1 was initially launched in 2023, and several versions have been released since. The most recent, Grok3, was announced and released in February 2025 for both Premium and free users. CEO Elon Musk has also been teasing an improved version of this model, Grok3.5, but that version is yet to release.

X

X (formerly Twitter) was acquired by xAI on March 28, 2025. As a result, the platform would be integrated further with xAI's models which are powered by Colossus. New features using this integration include a Grok-powered home feed and algorithm.

Choice of location

Musk and xAI chose Memphis for this project primarily because it offered a ready-made home for Colossus in the former Electrolux site. Musk was initially told that building the data center would take 18-24 months. He stated how this extended construction timeline “...means losing is a certainty…only option is to do it ourselves.” Musk instead began looking for a vacant and existing building, and this was when he found the Electrolux factory in Memphis, Tennessee. The global appliance maker Electrolux first opened the facility in 2012, but it shut down in 2020 to relocate to Springfield, Tennessee. The center is and was previously purchased by Phoenix Investors in December 2023 for $35 million. Using an existing space rather than building one from the ground up allowed the company to begin working on the computer immediately. Tedd Townsend, Greater Memphis Chamber president and CEO, revealed to Forbes that xAI had considered seven or eight other sites before selecting Memphis. Townsend also stated it took Musk about a week to finalize this decision to build the new supercomputer for xAI in Memphis. With this finalization completed in March 2024, the construction of the supercomputer started right away. The announcement that Colossus would be built in Memphis was made during a press conference in June.

The building was not the only incentive xAI had to choose Memphis, however. In the Greater Memphis Chamber’s website, it also states that the company chose Memphis because of its “reliable power grid, ability to create a water recycling facility, proximity to the Mississippi (River) and ample land." Altogether, the city had the ability to provide the massive amounts of energy needed to run the machine. The site continues to go into detail about how the AI company would benefit from the collaboration with local organizations such as Memphis Light, Gas and Water (MLGW), Tennessee Valley Authority (TVA), the City of Memphis, and Shelby County. It emphasizes the importance of these partnerships, especially once the supercomputer reaches full capacity, which will require millions of gallons of water daily and 150 megawatts of electricity. The city also provided financial incentives to the company, understanding how the presence of the supercomputer could turn Memphis into a tech hub. The ability of the Greater Memphis Chamber to expedite approvals and negotiations also allowed for the project's quick initiation, which was deeply important to Musk and the xAI team.

Environmental impact

AI requires more electricity to complete even simple tasks compared to typical search queries. A majority of the energy needed to generate the answers in AI queries comes from burning fossil fuels such as coal and gas, which are leading drivers of climate change. The United States is currently home to a third of the all data centers worldwide. Utility companies are adding new gas plants, while older power plants are redeveloped to meet the demand in a booming AI industry. Clean energy deployments cannot keep pace with the rapid expansion of AI data centers. AI requires power from thousands of servers that are contained in data centers, such as Colossus, and these data centers require "extensive amounts of energy".

At the site of Colossus in South Memphis, xAI applied to temporarily set up more than one dozen gas turbines, which would steadily burn methane gas. However, according to advocacy groups, aerial imagery in April 2025 showed 35 gas turbines had been set up. These turbines have been estimated to generate about "72 megawatts, which is approximately 3% of the (TVA) power grid". According to the Southern Environmental Law Center (SELC), the higher number of gas turbines and the subsequent emissions requires xAI to have a 'major source permit', however, the emissions from the turbines are similiar to the nearby large gas-powered utility plants.

In Memphis, xAI was able to sidestep some environmental rules in the construction of Colossus, such as operating without permits for the on-site methane gas turbines because they are "portable". The Shelby County Health department told NPR that "it only regulates gas-burning generators if they're in the same location for more than 364 days. xAI plans to eventually draw power from MLGW.

In the neighborhood of South Memphis, poor air quality has given residents elevated asthma rates and lower life expectancy. A ProPublica report found that the cancer risk for those living in this area already have four times the risk of cancer than what the Environmental Protection Agency (EPA) considers to be an acceptable risk.

Along with high electricity needs, the expected water demand is over five million gallons of water per day in "... an area where arsenic pollution threatens the drinking water supply." This is reported by the non-profit Protect Our Aquifer, a community organization founded to protect the drinking water in Memphis.

According to MLGW, their customers will benefit from the xAI project as well. The project is expected to create around 300 high-paying jobs. Additionally, xAI is partnering with the City of Memphis, MLGW and TVA to construct a "... graywater/recycled wastewater facility that will take in treated wastewater and produce water suitable for cooling processes," putting recycled wastewater to productive use and reducing the daily draw on Memphis' aquifer by up to 10 million gallons per day. Yet, there are no concrete plans for the promised wastewater facility, only the one-page factsheet shared by MLGW.

Community response

The plan to build Colossus in Memphis was kept secret from residents, City Council members, and environmental agencies in Memphis. Many did not find out about the project until the day before, or the day of as they watched the announcement on the local news. Keshaun Pearson, president of Memphis Community Against Pollution stated that there is a historical lack of transparency and communication surrounding environmental issues in Memphis. Some community members in Memphis have expressed concern about the potential for additional air and water pollution caused by the supercomputer. In a letter to the Shelby County Health Department, the Southern Environmental Law Center stated the emissions from the turbines make the facility "...likely the largest industrial emitter of NOx in Memphis..." This is due to data supplied by the manufacturer showing that "...xAI emits between 1,200 and 2,000 tons of smog-forming nitrogen oxides (NOx)..."

At a public Shelby County Commissioner's hearing on April 9, 2025, residents living near the site of Colossus voiced complaints about air quality noting that they have chronic respiratory issues related to living in a polluted section of Memphis. One woman said she smells "everything but the right thing and the right thing is the clean air." Other residents voiced frustration that Brent Mayo, the senior xAI official responsible for building out xAI's infrastructure, did not show up to the meeting to discuss concerns with the community.

Keshaun Pearson also stated that "We're getting more and more days a year where it is unhealthy for us to go outside." People living near the site of Colossus have said they were not offered the opportunity for a public review of the plans nor were they provided with information for how their community could potentially benefit.

The community is concerned about strain on the power grid as well. In November 2024, TVA approved xAI's request for access to more than 100 megawatts of power, enough electricity to power 100,000 homes, to Colossus which is supplied by MLGW. This fear is not unfounded, as the electric grid in Tennessee, including Memphis, has been strained during previous extreme weather events. In December 2022, MLGW imposed (then rescinded) rolling blackouts during several days of extreme cold that put a strain on the power grid. In a letter to the TVA, the SELC "urged the agency to 'prioritize Memphis families' access to reliable power over the 'secondary purpose' of serving xAI".

Current progress

In early December 2024, Ted Townsend detailed how the power of Colossus doubled in its processing capability. When it first went online, “it was using 100,000 Nvidia H100 processing chips.” Still, this initial launch demonstrated Colossus to be the largest supercomputer globally. The expansion of this supercomputer has already been discussed and will be the second phase of the project. It is stated that it will add 320 new jobs. Not only that, but in its expansion, xAI also plans to increase Colossus to 1 million graphic processing units. Since the current state of the supercomputer is using gas turbines for power, it is temporarily relying on them alongside Tesla Mega Packs. As part of this prospective expansion, xAI is also looking to add more Mega Packs, which could later allow the center to no longer depend on Memphis’s gas and water grid. Townsend also mentioned how xAI “is lsoexpected to act as a data hub for Musk's other companies, including X and SpaceX.”

The expansion continues as of recently, where xAI has purchased a site in the Whitehaven area of Memphis. This was announced by the Greater Memphis Chamber in early March 2025. xAI employee Brent Mayo states how the addition of this property “...ensures hey willremain at the forefront of AI innovation…in Memphis.” The property was bought for almost $80 million and transferred specifically to CTC Property LLC, an affiliate of Musk's xAI. The Memphis City Council has also approved xAI's wastewater recycling plant expansion. Plans for this expansion were initially revealed by the Tennessee Department of Environment and Conservation when preliminary plans for the facility were filed on September 18, 2024, for this project “...between xAI, Tennessee Valley Authority (TVA), and Nucor Steel...” At the time, xAI representatives detailed its estimated cost to be $78 million, which was to be privately funded. In March 2025, approval was officially granted for this expansion, including “...the sale of 13 acres for a wastewater recycling plant near the supercomputer in southwest Memphis.” The final cost of the project was revealed to be $80 million for construction.

See also

* Colossus: The Forbin Project

References

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External links

Memphis residents rally against Elon Musk's xAI project.


Inside the World's Largest AI Supercluster xAI Colossus.

Elon Musk finally reveals 'why Memphis' for xAI supercomputer.

AI supercomputers
Nvidia IP cores