Intel has begun selling its dual-core "Montecito" version of Itanium.

Hewlett-Packard, Unisys, Silicon Graphics, Fujitsu and NEC described plans for new Montecito-based servers at the chip launch event on Tuesday in the US. Most servers will arrive in September.

HP, which initiated the Itanium project and co-developed initial models with Intel, is by far the dominant Itanium server company. But Pat Gelsinger, general manager of Intel's Digital Enterprise Group, expects the market to even out.

"We expect the percentage will become greater for the other vendors going forward," Gelsinger said.

Whether that actually happens is a key barometer of whether Itanium is merely a replacement for HP's own server chips or, as Intel hopes, a broader market force that pressures IBM and Sun Microsystems' processor families more directly.

HP and Intel announced their chip collaboration in 1994, but the Itanium program has been fraught with delays and other troubles, including a Montecito delay in 2005. And though Dell and IBM dropped their Itanium servers, Itanium systems are encroaching on rivals' market share.

"I think we've hit critical mass," Gelsinger said.

Because the Montecito uses the same electrical connections as its predecessor, the "Madison 9M" Itanium, it can be dropped into the same servers. As a bonus, it consumes less power -- 104 watts maximum compared with 130 -- which means engineers don't have to worry about the common problem of overheating from a chip upgrade.

However, Montecito's dual processing cores have a greater appetite for data, and many server companies have chosen to design new servers around the chips. Although Unisys and Fujitsu are just upgrading the processor, HP, SGI and NEC built new machines for Montecito, company representatives have said.

The Montecito-Madison compatibility proved to be an advantage for HP and SGI, which had Montecito systems ready to go months ago. When Montecito was delayed, they introduced their new products with Madison chips.

Among the Montecito systems executives described at the launch event are the following:

• NEC is releasing two Express5800 models, the 32-processor 1320Xf and eight-processor 1080Rf, which run Windows or Linux. The systems feature internal communication technologies that keep the cache memories of many chips synchronized so they can fetch data faster and more effectively, said Mike Mitsch, general manager of NEC's alliances and strategy.
• HP will bring Montecito to its entire Integrity line, starting with lower-end machines and then later bringing it to the high-end Superdome products. HP doesn't plan any upgrade promotions, said Brian Cox, director of marketing for HP's Business-Critical Server group.
• Unisys will upgrade its ES7000 servers with Montecito-based models shipping in early September. The Montecito systems will cost roughly the same as previous Madison versions but will have twice the performance per chip, said Chas Weber, Unisys' director of enterprise server market development.
• SGI, which specialises in technical computing rather than business tasks, is using Montecito in its Altix 4700 and 450 machines, said Jill Matzke, SGI's marketing manager for high-performance computing. Raytheon is an early customer, buying two 384-processor Altix 4700 systems and one 512-processor system.
• Fujitsu announced three Montecito servers, the Primequest 580 with up to 32 processors, the 540 with up to 16 processors and the 520 with up to eight processors.