In 2005, Michael S. Dell’s namesake company was getting pounded. His competitors were selling personal computers and servers built on cheap, popular and powerful chips from Advanced Micro Devices, while Mr. Dell had stuck loyally with slower chips from Intel.

In an e-mail note to Intel’s chief executive, Paul S. Otellini, Mr. Dell threatened to switch to A.M.D. “I am tired of losing business,” Mr. Dell wrote. “We are losing the hearts, minds and wallets of our best customers.”

Mr. Otellini reminded Mr. Dell that Intel had paid Dell more than $1 billion in the last year. “This was judged by your team to be more than sufficient to compensate for the competitive issues,” he wrote. Dell delayed buying A.M.D. chips, and Mr. Otellini said in a later e-mail message to a colleague that Dell was “the best friend money can buy.”

Such payments to PC makers, along with other aggressive business tactics, are at the heart of the antirust lawsuit filed against Intel on Wednesday by New York’s attorney general, Andrew M. Cuomo. Mr. Cuomo’s case  the first antitrust charges against the company in the United States in more than a decade  follows similar actions by regulators in Europe and Asia.