Intel Corp. and Advanced Micro Devices Inc. are racing to introduce a dual-core computer chip in what could be the biggest change in PC technology in a decade.

Both companies have something to prove and both expect in a matter of months to launch products which essentially combine two microchips into one.

For Intel, the transition offers a chance to shake off a year's worth of missteps and delays with an on-time product introduction; for AMD, the change amounts to its best opportunity in years to take business away from Intel, its much larger arch-rival.

Having approached the limits of speed gains with traditional chips, Intel and AMD have moved to combine two chips onto a single piece of silicon.

The result is one chip with two cores that can operate independently -- with one, for instance, processing a television show while the other scans for viruses.

For some applications -- like the multimedia processing that is seen as a key path for PC industry growth -- dual core shows major gains. "On some benchmarks, it just blows everything away," said Martin Reynolds, an analyst with Gartner Inc.

Intel on Monday turned heads in the computer industry by allowing independent reviewers to publish performance tests on its first dual-core computer chip, called Extreme Edition, before it becomes officially available. The reviews were generally positive, though some noted the chip's high heat production.

Intel generally keeps reviews under wraps until it launches a chip with PC partners. On Tuesday, Intel President Paul Otellini announced in Washington that the dual-core chips would become available in May, within the previously announced second-quarter time frame, said spokeswoman Laura Anderson.

AMD, which has set a "mid-year" target release for its dual-core chips, is dropping hints that the product may arrive sooner. It has told the media to expect important news at a New York event on April 21 to mark the two-year anniversary of its Opteron chip for business PCs, known as servers.

Opteron has not rescued AMD's market share, despite a major push. AMD's share of the market for PC microprocessors dipped nearly a percentage point last year to 15.7 percent, while Intel gained a point to 81.5 percent, IDC figures show.

But it would take a persistent marketing effort and flawless manufacturing for either company to steal business from the other, said Apjit Walia, an analyst with RBC Capital Markets. "It's a lot like Coke and Pepsi," he said. "It has less to do with taste. It's branding and execution."