It's a summer day in Santa Clara, California, and an assortment of luxury cars - Porsches, Corvettes, Lamborghinis - take up parking spots previously occupied by humbler models. Some have new paint jobs in the lime green from Nvidia Corp.'s logo.

And they are stuck where their owners want to be: at the office. Nvidia stock has gained 3,776% since the start of 2019 as the company benefits from selling the main chip necessary for artificial intelligence work, minting many new multimillionaires in the process. But the work hours are just as gruelling and high-stress, current and former employees said, leaving little time for the jet-setting, homebuying and leisure many can now afford.

A culture problem is brewing, said the 10 people, who asked not to be identified for fear of retribution. The 31-year-old chipmaker has piled on market cap faster than any other company in history. Founder and Chief Executive Officer Jensen Huang has established expectations of scrappiness and overworking, with a chaotic structure where one manager can have dozens of direct reports, the current and former employees said.

Rather than firing employees like his competitors, Huang has said he prefers to "torture them into greatness." One former employee, who worked in technical support for enterprise clients, said he was expected to work 7 days a week, often until 1 a.m.

or 2 a.m. He said many of his former colleagues, especially those on engineering teams, worked longer hours.

He described the environ.