The boffins at Microsoft are experimenting with low-powered servers using Intel's inexpensive, but efficient Atom processors, designed for netbooks.

Though slow compared with state-of-the-art multicore server CPUs, Atom processors draw less electricity to run and cool them - as little as one-twentieth of the energy required by conventional server processors, according to Jim Larus, director of software architecture at Microsoft Research, speaking at the company's TechFest earlier this week (YouTube video downloadable here).

"They're not as powerful, so you may require many more of these servers in the data centre, but since each one consumes less energy, the data centre as a whole can be more efficient and get more work done for the same amount of energy," he said.

Data centre operators are keenly aware today that the cost of the energy to power a data centre over time is far greater than the cost of the server hardware itself.

In the video, Larus shows a prototype server rack holding 50 Atom systems, which, because of the low heat generated by the Atom, doesn't require a powerful fan for cooling the rack, though there are still fans for each individual Atom CPU. These could be used in Microsoft's massive data centres alongside conventional servers and servers deployed in shipping containers.

Microsoft is also working on software tentatively called Marlowe to take advantage of the Atom's fast sleep/wake features, according to an interview with Dan Reed, director of scalable and multicore computing at Microsoft.

Because they were designed for laptops and netbooks, Atom CPUs can be quickly put into sleep/hibernate states and then quickly woken up, said Dave Ohara, a consultant who runs the Green Data Center blog, unlike desktop and server CPUs.

According to Microsoft, today's average server sits idle 75 percent of the time. Putting idle Atom servers to sleep could cut their energy usage by another 90 percent, says Microsoft, to about 3 to 4 watts for the entire system.

Judging by the $300 (£211) to $400 cost of Atom-based netbooks, Ohara said that racks of Atom-based server blades could be made for even less.

"Intel hates this, because they want to sell you more expensive multicore Xeon processors," Ohara said. "But sometimes small is more beautiful."

Intel did not immediately return a request for comment.

Microsoft isn't the first to look at Atoms for servers. Last May, Tranquil PC, a Manchester, UK-based PC maker, began selling home servers using the Atom.

SingleHop, a Chicago hosting provider, began leasing dual-core Atom servers to customers in October. According to a post at SingleHop's blog, the Atom server is "faster than a Pentium 4" and uses 75 percent less power.

While Microsoft is looking at Atom servers for its own large-scale data centres, Ohara says Atom servers would be potentially more useful for small to medium-size businesses that prefer retaining security and control of their own servers over storing their data and using the applications of a cloud-based service such as Salesforce.com or Amazon.com's S3.

"If you have a low-load situation, like most SMB servers are, an Atom can work fine," he said.