Intel is to build its next generation of desktop processors on the more power-efficient architecture created for its mobile processor, the Pentium M, sources have revealed.

At some point in 2005 or 2006, Intel will begin to phase out desktop processors based on the NetBurst architecture of the Pentium 4 in favour of the Banias architecture. Before then, Intel's next P4-style processor Tejas, and the successor to the Pentium M, Dothan, will be released. But by the time it introduces the (mobile) Merom processor in 2006, a shift to the mobile-chip architecture will be underway.

After years of ever-increasing frequency and transistor counts, the semiconductor industry has realised that in order to continue to shrink chip sizes and increase performance, it needs to develop chips that sip, instead of guzzle, power.

Enterprises have become more aware of the power cost of keeping a company full of computers up and running, and home PC users are gravitating towards what Intel calls entertainment PCs - small, quiet PCs that sit in the living room rather than the office and control a home media network.

It was notebooks, where power consumption is a main concern, that sparked the creation of the Pentium M processor, first known by its Banias code name. Banias was said to be a combination of the power-efficiency of Intel's Pentium III chip and the performance of the Pentium 4 processor. Notebooks based on the chip won excellent reviews for both their battery life and system performance.

Power-efficient chips allow PC designers to free up space within desktops that had been allocated for sophisticated cooling equipment, and either add additional features or reduce the size of the PC. Many PC analysts and vendors feel that consumers won't put PCs in their living rooms unless they eliminate the loud cooling fans required to maintain optimal performance in current desktops.

Intel's engineering team actually uses a number of small PCs from Shuttle that are smaller and quieter than traditional desktops, but could become quieter with a more efficient processor.

A chip design that does a good job of managing power consumption also allows for the development of dual-core processors for desktops and notebooks. By adding two processor cores on a single chip, designers can increase performance without having to increase the frequency - and therefore power consumption - of either core.

Intel's plan makes sense in that it would be difficult to place two Netburst cores on the same die, said Kevin Krewell, editor-in-chief of the Microprocessor Report. The Banias cores are much smaller and more power efficient, and are easier to incorporate into dual-core designs without increasing the size of the chip, he said.

IBM and Sun have already released dual-core processors for the server world, and Intel will follow with dual-core Itanium and Xeon server chips in 2005. But server processors are a premium product where die size isn't as important a consideration, Krewell said.

Yonah will be Intel's first dual-core processor for notebooks. It's unclear if Yonah or Merom will be the chip that Intel shifts into the desktop product line, but future Intel desktop processors will be based on the Pentium M architecture present in both those chips.

Intel will need to add support for SSE3 extensions and hyperthreading technology in order to ensure the new Pentium M-based chips can handle the increased performance requirements of desktops and entertainment PCs. Dothan is not expected to feature either of those technologies.

An Intel spokeswoman declined to comment on unannounced products.