Nvidia is in talks to provide a $250 billion backstop for a planned OpenAI data center in southern Ohio.

The SoftBank facility could cost more than $500bn, consume 10GW, and be the largest ever data center. Its first phase is expected in 2028, at around 800MW.

The Wall Street Journal reports that Nvidia’s backing would allow SoftBank to raise debt at more favorable terms, making the facility more viable.

The project was first announced this March on Department of Energy land, currently home to a decommissioned uranium-enrichment site. SoftBank subsidiary SB Energy is set to build 10GW of new power generation, including 9.2GW of natural gas generation, to power the facility. OpenAI is also an SB Energy investor.

As part of a broader trade deal, Japan agreed to invest $33 billion in the natural-gas power project operated by SB Energy. The US government will reportedly pay SB Energy to operate the project, one of the people said. Japan and the US will split the power sales until Japan recovers its investment, after which the American government will get 90 percent of the revenue, the WSJ reports.

Under the Nvidia backstop deal, which is still under negotiations, the GPU giant would guarantee a series of financing vehicles behind the project. The guarantees would focus on the data center buildout and lease, and not the purchase of the chips set to go into the site.

Nvidia has invested $30bn into OpenAI, and is separately in talks to help finance as much as $350bn in chip sales to the company.

As the costs of deploying AI at scale continue to grow, Nvidia has increasingly moved to back its customers. The company has been in talks to guarantee a number of OpenAI loans since last year, has backed $860m in lease obligations for an undisclosed partner's data center, and has signed a $1.5bn deal to lease its GPUs back from Lambda.

This month, the company announced that it would rent back unused GPUs at a fixed rate from neoclouds, with Firmus and Sharon AI signing on.

Google has similarly backstopped loans for Fluidstack lease obligations, with the neocloud set to deploy Google TPUs.