AMD is adding a new, low-power Opteron processor to its Shanghai line roadmap and it plans to release the chip in the second quarter of the year.

The company said the need for lower-power chips was being driven, in part, by the rise of computing cloud centres, the massive data centers being built by the likes of Microsoft and Google to deliver cloud services.

AMD isn't saying, just yet, how much it can cut power usage in the upcoming 45nm, quad-core chip line below the power used by its current low-power chip, a 55-watt processor released today. AMD revealed its plans for the fourth chip as part of the release of two new processors.

In November, AMD released the first in its line of 45nm, quad-core Opterons, a 75-watt version with speeds of up to 2.7GHz that makes up the bulk of sales in the Shanghai line. It has now followed that processor with two more: A 105-watt, 2.8GHz chip designed for high performance and large database users, and the 55-watt version, which offers speeds of up to 2.3GHz. That latter processor may appeal to cloud-centric facilities and large hosting data centres.

These chips succeed similar offerings in the 65nm Barcelona line of processors.

The decision to add the fourth chip to the line follows AMD's announcement last fall that Microsoft would use its Opteron chip for its cloud computing initiative, the company's Windows Azure Compute Service. AMD isn't alone in looking to diversify its chip line to address escalating heating and cooling problems in data centres. Rival Intel, for instance, last year released a 50-watt Xeon chip.

AMD said the new chips were available immediately on servers from Hewlett-Packard  and Rackable Systems.  Servers using these chips will be available from other vendors this quarter, including Dell, IBM and Sun.

At one time, a low-power chip with lower clock speeds would have been a niche product.. But this niche is growing. Cloud computing is really a high-growth segment, said Steve Demski, a senior product manager at AMD. As a result, the chip maker is expecting demand for low-power chips to increase with the rise of cloud computing as a platform.

Lower power, combined with a virtualiation-optimised processor, fits cloud-computing environments looking to save as much on energy consumption as possible, said Charles King, an analyst at Pund-IT.