Elon Musk’s xAI has raised $20 billion to help fund its data center build-out.

The startup, developer of the Grok chatbot, has pocketed the cash in an oversubscribed Series E funding round. Previous reports had suggested it was hoping to raise $15bn at a valuation of $230bn.

Financial backers include Valor Equity Partners, Stepstone Group, Fidelity Management & Research Company, Qatar Investment Authority, MGX, and Baron Capital Group, xAI said on Tuesday.

Nvidia and Cisco were named as “strategic investors” in the Series E round.

“This financing will accelerate our world-leading infrastructure buildout, enable the rapid development and deployment of transformative AI products reaching billions of users, and fuel groundbreaking research advancing xAI's core mission: Understanding the Universe,” the company said.

xAI operates two data centers in the Memphis area, which power its Colossus supercomputer, the machine used to train and run Grok. One of the data centers is in the city itself, and another is just over the border in Mississippi. In December, Musk announced the firm had bought a third building nearby, and plans to turn it into a data center that will bring the company’s available compute power to just under 2GW.

The company has a stated aim of expanding Colossus to a point where it uses 1 million GPUs. On Monday, analyst firm SemiAnalysis said that xAI had purchased five natural gas turbines from South Korea's Doosan Enerbility, each of which will be capable of providing 380MW of power. The first two turbines are scheduled for delivery by the end of the year, the report said, and once all five are in situ, they will provide enough power for 600,000 GPUs.

While the speed of its data center buildout has been impressive, utilizing gas turbines and Tesla megapack batteries to bring capacity online fast, xAI has also attracted criticism from community and environmental groups in Memphis, which have questioned the impact of the data centers and their turbines on air and water quality in the area.

xAI raised $10bn in debt and equity last year. It is unclear if Nvidia’s involvement in the funding round is separate from a deal revealed in October, which will see the GPU maker invest up to $2bn in xAI via a special purpose vehicle linked to the company.

On Monday, DCD revealed xAI had poached AWS’s head of data center networking for a machine learning-focused role.