Intel has launched two new quad-core Xeon processors incorporating virtualisation and energy efficient features that promise cuts in power usage.

The processors -- designed for companies running performance-critical server and workstation applications -- employ system-transparent energy smart technology that Intel claims slashes idle power usage by up to 50 percent.

The Xeon X5365, a 3.0GHz processor, is priced at US$1,172 while its sibling, the 2.0GHz Xeon L5335 is US$380 -- when ordered in quantities of 1,000 units or more. Both have a 1333MHz FSB.

According to the chipmaker, the Xeon X5365 is "the industry's first 3.0GHz quad-core processor to fit inside a standard 120-watt power envelope" (30W per core). The L5335 has a 50-watt power envelope (12.5W per core).

In addition the X5365 and L5335 support both 64-bit and 32-bit desktop operating systems.

Vendors supporting the new processors include Dell, Fujitsu Siemens Computers, Hewlett-Packard, IBM, Rackable Systems, SGI, SuperMicro and Verari.

This news follows on from AMD's announcement of its low-voltage, quad-core, "Barcelona" Opteron processors last month, and Phenom, its soon to be launched quad-core desktop processors.

It's been a rough stretch for AMD's server business of late. The company has cut the prices of its server chips to deal with Intel's latest dual-core and quad-core server processors, which contributed to disappointing fourth-quarter earnings and still didn't prevent the loss of some server market share to Intel.

Intel plans to up the ante later this year, with a chip and chipset for dual-processor machines that communicate at 1600MHz compared with today's 1333MHz front-side bus. Improving that speed reduces delays fetching information from memory.

Stephen Shankland and Tom Krazit from CNET News.com contributed to this report.