SAN FRANCISCO (AP) -- Two executives have left Advanced Micro Devices Inc., including the head of the slumping chip maker's microprocessor division, as the company tries to engineer a dramatic turnaround to fend off larger rival Intel Corp.

The Sunnyvale-based company said Monday that Mario Rivas, executive vice president of the computing solutions group, and Michel Cadieux, chief talent officer, have resigned from AMD to ''pursue new opportunities.''

Rivas oversaw AMD's microprocessor business, which produces more than two-thirds of the company's total sales and has been under pressure the past two years.

AMD's sales have been dampened by intensifying competition from Intel and by technical glitches that delayed the launch of AMD's new Opteron server chip by eight months.

Rivas has been replaced by Randy Allen, who's been with AMD 24 years and most recently led the company's server business.

AMD did not disclose the reasons Rivas and Cadieux resigned, other than saying they were part of a series of management changes connected to the company's ongoing restructuring efforts.

AMD has lost more than $4 billion since the last three months of 2006 and its stock has fallen from over $40 in 2006 to around $7 today. Last month the company announced plans to jettison about 1,600 workers out of 16,800 worldwide, in an overhaul expected to be finished by September.

The departures of Rivas and Cadieux come one month after AMD's chief technology officer, Phil Hester, resigned for undisclosed reasons. AMD said Hester's departure was not related to the company's restructuring.

AMD shares rose 22 cents, or 3.2 percent, to close at $7.16.