After months of delays, Advanced Micro Devices' quad-core Barcelona chip will become generally available in April, but a newly announced six-core processor developed by rival Intel will force AMD to play catchup once again.

Intel on Monday said a six-core processor code-named  Dunnington will be available in the second half of this year. AMD, meanwhile, will ship Barcelona to partners later this month, making it broadly available from resellers sometime in April, AMD vice president of commercial business Kevin Knox told Network World this week.

"Barcelona is a step up but it's really too late," says Gartner analyst Martin Reynolds. "They needed Barcelona in the second half of last year."

Barcelona, the code name for AMD's newest Opteron processor, is in limited availability and being used mostly in high-performance computing facilities such as the Texas Advanced Computing Center and the Holland Computing Center at the University of Nebraska. AMD initially planned general availability for the end of 2007, but AMD held back after discovering a problem at high-stress workloads. "We went ahead and fixed it in the silicon," Knox says. "Systems would hang for certain things, virtualization wasn't performing properly. It wasn't data corruption."

Intel has had quad-core Xeon processors on the market since early 2007 and in September unveiled the Xeon 7300 quad-core chips, which are designed for high-end servers with four or more processors.

Even with Barcelona hitting general availability, AMD's performance lags behind Intel in processor speed and bandwidth utilization rates, according to Reynolds. "It's going to be Intel winning the performance battle for the next year and a half," he says. "But you can never count out AMD and we'll see what they deliver in 2009."

Knox says AMD's newest chip will deliver better performance than Intel, and that new instructions at the chip level will enable virtualized workloads to operate more efficiently on the processor. Customers will see a sizable improvement in price performance per watt, he says.

"We've gone from dual to quad-core while maintaining the same thermal envelope," Knox says. "This is more than just quad-core. It is a significant re-architecture of Opteron, the most significant since we've introduced it."