AMD is to include a triple-core chip in the line-up for its forthcoming Phenom desktop processors. The company said there is a gap in the market for a product with more performance than dual-core chips, but which costs less than current quad-core processors.

Phenom is AMD's quad-core chip for desktops, set to debut in December 2007. However, the company said it has updated its roadmap to include a triple-core version that will ship in the first quarter of 2008.

"Our research shows that the competition is having trouble getting demand for their quad-core parts. Triple-core hits the sweet spot for users that need more power than dual-core, but don't want the high price associated with quad," said Brent Barry, AMD's product manager for desktop.

The triple-core Phenom will be a quad-core part with one of the cores disabled, and Barry hinted that AMD might be able to meet demand partly through using quad-core parts where one of the processor cores does not meet quality controls.

In terms of performance, AMD said it expects the triple-core Phenom to fall between dual-core and quad-core, but declined to give specific figures.

"We're seeing serious uplift going from dual to triple. When looking at multi-threaded applications, you will see a significant gain," Barry said. He added that the additional core would likely give a boost to users running Windows Vista.

"Absolutely, Vista is a very demanding OS, and users are more and more taking advantage of PCs to do multi-tasking. There's a definite niche and a definite need (for triple-core)," he said.

The processor cores used in the Phenom line are very similar to those in AMD's 'Barcelona' Quad-Core Opteron, which the firm launched last week. However, there are differences in the overall chip design. The Phenom chips have a faster memory bus and fewer HyperTransport links, for example.

"We made choices (for the desktop) based on features we thought users wanted, so there is some divergence from the server chips," said Barry.