Intel has released its latest "Tulsa" dual-core server processers.

The news was accompanied by dozens of server manufacturers, including HP, Dell and Unisys, announcing plans to incorporate the 64-bit Xeon 7100 processor into upcoming servers. Tulsa is Intel's response to AMD's Opteron 800-series processors, the most recent challenger to its dominance in the server processor market.

HP Tuesday announced that Tulsa will go into upgraded versions of its x86 platform ProLiant 500 series servers. HP says that offering ProLiants with the Tulsa chip will strengthen its market share lead in the x86 processor segment

Dell is offering Tulsa in new versions of its PowerEdge 6800 and 6850 servers. The company reported performance gains of up to 123 percent and performance per watt gains of up to 129 percent, compared to servers running Intel's Paxville-MP chip line, the predecessor to Tulsa.

Unisys said it plans to use Tulsa in its next generation ES7000 sometime in the fourth quarter, and later in its ClearPath server lines. Unisys does not use AMD chips, said Mark Feverston, director of enterprise servers and storage at Unisys.

Intel has however lost significant market share to customers who weren't happy with the company. In April, AMD claimed its share of the x86 processor market had grown to 22 percent from just 7 percent a year earlier.

"It certainly added to our sense of urgency," said Tom Kilroy, vice president of Intel's digital enterprise group. But he also said Intel launched Tulsa to meet customer demand for processors that increased performance while reducing energy consumption and enabling virtualisation.

Tulsa, based on a 65-nanometre chip design, is built to run on servers with four or more processors, Intel said. Tulsa's cores run 13 percent faster than Paxville, while using 20 to 40 percent fewer watts, the company said. Intel builds each Tulsa chip by combining two 3.4GHz Pentium 4 cores on a single die, and will deliver both 150W and 95Wversions. Tulsa supports four threads per processor and has a 16MB cache, compared to a 4MB cache in Intel's Woodcrest processor, another member of the Xeon family introduced in June.

Intel will use the Tulsa chip to fill a gap in its line between the Woodcrest Xeon 5100 and the Montecito Dual-Core Itanium 2, said Shane Rau, an analyst with IDC. "With Itanium, users are looking primarily at performance, and with Woodcrest they are looking at price. Something like Tulsa will go right down the middle," he said.

Ben Ames, in Boston, contributed to this report.