In late 2007, Robert Hormuth called a former colleague he had worked with when they were both at Intel: Ian Drew, now a marketing vice president at ARM Holdings in the UK. Hormuth had moved on to Dell Computer’s Server and Architecture team, and wanted to explore a new idea.

Instead of relying exclusively on Intel’s powerful microprocessors to build the servers that handle billions of bits of data flowing through datacenters every second, would it be possible to use smaller, less powerful and lower-power ARM chips, now popular for cell phones and other hand-held devices?

“We thought ARM would be interesting for a web server or home server,” explains Hormuth, Senior Distinguished Engineer at Dell. “So we started kicking some tires in late 2007, early 2008.”

It seemed counter-intuitive at the time. But Dell’s Server & Architecture group had been watching the incredible growth in data moving though the Internet and the growing cloud computing business. They conducted a study of computer infrastructure at Fortune 500 companies. “The results were surprising and shocking,” says Hormuth. “They don’t need all the horsepower being thrown at them. They were just sitting there using up watts.” The big promise, of course, is that ARM chips use much less power than Intel’s powerful Xeon line of processors – about five watts vs. several tens of watts for Intel’s traditional Xeon chips.

The folks at ARM Holdings also thought it was a promising idea. “Dell approached us and started talking about the power challenges they were facing,” says Ian Ferguson, vice-president of marketing at ARM Holdings. “On the strength of that we started to do some work,” exploring the idea that small-core processors could better handle the task of moving data through datacenters.

A couple years later the organization started hosting a website with a server run by an old, and definitely inadequate, ARM-based processor, just to see what problems would come up and what design changes might be needed to fix them.

In 2012, the ARM architecture has begun to show real promise – or at least interest from chipmakers, server manufacturers and datacenter operators. AMD, Applied Micro, Calxeda, Marvell and Qualcomm are moving into the server-class ARM chip or system-on-chip (SoC) business, and Samsung is rumored to be doing the same. Dell, Hewlett-Packard, and Penguin Computing are starting to build ARM-based servers. Facebook has professed a strong interest in low-power server chips and is keeping an eye on both ARM and coming Intel chips.

The race to build low-power processors for datacenter servers has officially begun. Intel is pitting its low-power Atom processors against an array of ARM competitors. Most server makers are likely to continue to use Intel chips as they wait for the market to sort itself out, but the future will depend on how well each player rises to the need for more efficient processors.

It’s an important race to Intel. Its processors are at the core of over 90 percent of datacenter servers today. That market is a small fraction of the PC business. Some 90 million PCs were shipped in the last three months of 2012, and Intel owns about 80 percent of that market. But that number also shrank by five percent compared to the same period in 2011. Standard PCs are being displaced by tablet computers, smart phones and other portable devices. Intel has not been very successful moving into the new consumer products market, losing out to ARM and other processors. It does not want to lose the growing server market as well.

For the last two years Intel has asserted that the microserver business that will use ARM and other low-power chips is likely to represent just 10% of the market in datacenters. Further, Raejeanne Skillern, director of the Cloud Computing Data Center Group at Intel, says that two-thirds of that market will go to “brawny” core chips, with higher compute power than the “wimpy” core chips that ARM largely represents. But a lot of people disagree with that assessment. “The microserver market is going to be more important than Intel would argue today,” says Nathan Brookwood, Research Fellow at semiconductor consulting firm Insight 64.

Datacenter servers are of huge importance today, because they run the Internet. Companies don’t just use information technology to run their own businesses, IT is their business. Servers are not just a back-office expense item, they are a big part of many companies’ product costs. Modern tech giants, including Amazon, Apple, eBay, Google, Facebook, Microsoft and Yahoo deliver their services through datacenter servers. The less expensive the server (and the datacenter,) the lower the cost of producing their products.

There are several factors that will enter into the race. Low-power is a huge issue. Another is whether there are 64-bit processors available, and how much memory the chips can handle. A third depends on which applications the servers will run and how easy it will be to port software to the different chips. One of the most critical technology issues is the on-chip “fabric” that will tie together different components of the SoC to make sure they run at peak efficiency. Chip manufacturing technology and the balance between open or proprietary products will also play a role.

Next: Power – Less is More >

Power: Less is More

“Among the customers that we serve, both HPC as well as large web farms, one of the common themes that comes up is that in the world of semiconductors today, it’s all about performance per watt,” says Charles Wuischpard, CEO of Penguin Computing.

Although supercomputers crunching complex floating-point instructions need powerful CPUs, they also need to lower their power consumption or their growth will be limited by the sheer cost of electricity to run them. Adding co-processors and ARM chips into the mix to handle appropriate functions can help. Penguin makes servers with X-86 processors from Intel, but last fall announced a new microserver based on an ARM SoC from Calxeda.

And demand from datacenters keeps increasing. “I’ve seen estimates that demand for cloud computing is increasing anywhere from 20% to 44% per year,” says Mike Major, vice president of corporate marketing for Applied Micro. If the datacenters don’t dramatically increase their efficiency, he says, in a few years “datacenters are going to account for the better part of seven percent of the world’s energy consumption.”

ARM chips, designed for small portable devices, were created to survive on little power, which is a big part of their appeal. “The energy efficiency story is clearly an important one,” says Drew Schulke, product marketing manager for Dell’s Data Center Solutions business.

That goes beyond just how much power the chips themselves draw. Low-power chips generate less heat, reducing the need for expensive cooling equipment. Smaller chips built into microservers can take up less space, leaving smaller areas to cool.

But competing claims are hard to decipher. Intel boasts that its 6 watt S1200 Atom chip is the lowest-power 64-bit processor on the market. That may be, but it doesn’t really match the power efficiency of today’s ARM chips. “The only way you can say the S1200 has low power is to say that it’s way less than Intel’s mainstream Xeon chips,” says Insight 64’s Brookwood.

Calxeda, for example, has circulated a table comparing its own ECX1000 SoC to Intel’s S1200. The ARM chip draws 3.8 watts, compared to 6.1 watts for the S1200. Further, it provides four cores, compared to Intel’s two, and has a cache memory of 4 gigabytes compared to Intel’s 1GB. Plus, the S1200 is not a full “server class” solution because it doesn’t include a Serial Advanced Technology Attachment (SATA) microcontroller, Ethernet, or a fabric switch or fabric ports. Adding in those features would require an extra 10 watts of power, agrees Brookwood.

Intel, however, points out that the S1200 is a 64-bit processor. “It’s almost impossible to compare,” notes Intel’s Skillern. Plus Intel continues to work on future products that will be more efficient, including the upcoming Avoton. And in the end it’s not all just about the chip. Virtualization will also decrease the energy sink of a datacenter. “We have not been sitting still in either technology or IP,” says Skillern. “We have a history of investing and innovation.”

Even Ferguson at ARM Holdings agrees with that. “Intel is a very, very competent organization,” he says. The market for datacenter servers, he adds, “is not a game they’ll just give up on and let ARM walk in.”