AMD is set to officially launch its Barcelona quad-core Opteron processor at a company event in San Francisco later today.

The event will focus on partners supporting the 65nm chip. Server vendors including Dell, HP, IBM and Sun Microsystems are scheduled to unveil systems based on AMD's latest chip.

Sun plans to upgrade most of its existing line of AMD servers to the new processor, and to build a Barcelona version of the four-socket, 2u Intel Xeon server that it showed off last week at the launch of Intel's four-processor Xeon.

Sun has not yet released a product name for the server, but said that it will be made available in the next two months.

The number of system builders supporting AMD's Barcelona stands in stark contrast to the launch of the first Opteron in 2003, when IBM was the sole vendor supporter. Sun did not join the party until September 2005, and Dell held out until 2006.

Opteron allowed AMD to gain initial market share against Intel. The chip offered better energy efficiency than its competitor, and Intel was struck by a slew of embarrassing product delays that made it fall behind it smaller rival.

Intel has been able to gain back its footing over the past year, however, and started shipping quad-core Xeon processors last November.

AMD then suffered product delays of its own which put it 10 months behind Intel in the release of quad-core processors.

The firm also disappointed observers by shipping only a 2GHz quad-core Barcelona. Faster models are scheduled to ship by the end of this year, but AMD for now trails behind Intel's 3GHz quad-cores.

Barcelona does have the better architecture, however. AMD engineers designed the chips with all four cores on a single die, whereas Intel depends two dual-core dies packaged in a single chip.

Intel's design causes higher energy consumption as well as decreased performance.

"The real question is whether AMD's architectural advantage can trump Intel's frequency advantage," said Nathan Brookwood, an analyst with Insight 64.

Although Barcelona allows AMD to take back the performance lead from Intel in some areas, Intel is expected to gain the edge early next year when it starts shipping a 45nm version of its quad-core Penryn processor.

AMD's challenge is to sign up as many customers and partners before Intel takes back the lead, but it is facing another issue here.

When Intel launched its quad-core Xeons last year, it made sure that system builders were well stocked even before the official launch to allow them to prepare their systems.

"For AMD that tyre-kicking phase is just going to begin," noted Brookwood.