Just because they have cash doesn't mean they're going to lay it all on the table for one risky business. Which is why the actual solution is mostly loans.
In being a guarantor, Nvidia isn't directly giving the money now, but it is promising to be liable for the loan if OpenAI defaults. That's a risk they have to budget for.
But in addition to being a guarantor, they're also loaning out chips:
"OpenAI plans to pay for Nvidia’s graphics processing units (GPUs) through lease arrangements, rather than upfront purchases." "By leasing the processors, OpenAI can spread its costs out over the useful life of the GPUs, which could be up to five years a person said, leaving Nvidia to bear more of the risk."
Nvidia is leasing them the GPUs, which is basically a loan.
"In addition to offering a cost-efficient way for OpenAI to access chips, Nvidia’s lease option and long-term commitment can help the company land better terms from banks when it comes to raising debt, a person said. "
"As a non-investment-grade startup that lacks positive cash flow, financing remains costly. OpenAI executives have called equity the most expensive way to fund data centers, and said that the company is preparing to take on debt to cover the remainder of the expansion."
"“Folks like Oracle are putting their balance sheets to work to create these incredible data centers you see behind us,” Friar said. “In Nvidia’s case, they’re putting together some equity to get it jumpstarted, but importantly, they will get paid for all those chips as those chips get deployed.”"
Nvidia leases (loans) them GPUs with a promise to pay for them later. Getting this lease (loan) from Nvidia helps them secure more debt.
"OpenAI’s path to a $500 billion private market valuation has been enabled by hefty investments from Microsoft and others that allow the company to burn billions of dollars in cash while building its AI models that power services including ChatGPT."
"Jamie Zakalik, an analyst at Neuberger Berman, said the Nvidia deal is the latest example of OpenAI raising money that it pours right back into the company providing the capital. Investors are concerned about the “circular nature of this deal goosing up everyone’s earnings and everyone’s numbers,” said Zakalik. “But it’s not actually creating anything.”"
They get a loan of chips, use it to get a loan of money from someone else, and spend that money on the company that loaned them the chips. It's a Ponzi scheme.
(https://www.cnbc.com/2025/09/24/nvidia-openai-investment-in-...)