Internet data center power requirements are rising as much as 20 percent a year; already, according to experts' estimates, these facilities in total consume as much electricity as some countries, including Iran, Mexico, Sweden and Turkey. The industry hopes to reverse the trend by revisiting the design of cooling systems, power supplies and server architectures.

In servers, the notoriously voracious microprocessor is passing the power-hog mantle to the DRAM, which offers fast data access but requires a heat-generating refresh every few milliseconds. Thus the greening of the data center includes a focus on lower-voltage DRAMs, nonvolatile alternatives and the emerging category of storage-class memories.

Whether the green-memory movement thrives or dies on the vine, the DRAM status quo could be uprooted.

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The DRAM's power appetite is not its only problem. As the recession wears on, OEMs are keeping a nervous eye on struggling memory suppliers. "It's not pleasant to see our partners suffer so badly," said Tom Lattin, director of strategic commodities for industry-standard servers at Hewlett-Packard Co.

DRAM scaling, meanwhile, could hit a wall as it becomes increasingly difficult to shrink the capacitor within the device. That could fuel the need for such alternatives as ferroelectric, magnetoresistive, phase-change and resistive RAM.

Don't look for the DRAM to disappear, said Bob Merritt, an analyst with research firm Convergent Semiconductors who believes DRAMs will scale to 20 nanometers. "There will be DRAM applications for the next 10 years," Merritt said, but "you will also see applications" that will turn to nonvolatile alternatives (which don't require refresh to maintain the data) for server main memory.

Bill Tschudi, program manager at Lawrence Berkeley National Laboratory, said the drive to make data centers more power efficient will include better IT practices, new power distribution schemes, higher processor utilization rates and "advancements on the memory side."

"Memory power is a significant portion of platform power," noted Dileep Bhandarkar, distinguished engineer with Microsoft Corp.'s Global Foundation Services unit. "As processor performance increases and virtualization takes off, the memory footprint will increase. There is a need for lower-voltage DRAMs."

DRAM makers have responded with lower-voltage DDR3 synchronous DRAMs, which have found a home in servers from such vendors as HP, IBM, SGI and Sun.

Meanwhile, solid-state drives (SSDs) and I/O accelerators could shake up the memory and storage hierarchy. And server startups Schooner Information Technology Inc. and Virident Systems Inc. have released data center servers that promise to cut hardware costs as well as power consumption. The potential of the technology has prompted IBM to form an alliance with Schooner.

In theory, green servers could replace traditional X86- or RISC-based systems, possibly displacing DRAM in the process. Schooner and Virident use lower-power, nonvolatile, "storage class" memory to handle the search index and other tasks usually relegated to DRAM.

Market watcher Frost & Sullivan estimates that a typical server farm of 5,000 systems with 32 Gbytes of DRAM each could be reduced to 1,250 systems with 128 Gbytes each of nonvolatile memory, resulting in a 75 percent reduction in energy over four years, a 75 percent reduction in the cost of physical space and a 45 percent reduction in capital expenditures.