Heat, that nasty by-product of computer processing, is a data center's worst enemy. Excessive heat fries CPUs, crashes servers, drains performance, taxes cooling systems, and ultimately sucks electricity. The problem is getting worse as tightly packed racks of servers raise temperatures ever higher, sending the industry scrambling to avoid a meltdown. One solution: water, what else?

Tech vendors from startups to Hewlett-Packard and IBM are developing data center cooling products that squirt liquid onto a computer's hot spots. In some cases, specially treated, nonconductive, noncorrosive H₂0 is used. In others, it's something more esoteric, but the goal is the same--to whisk away heat as efficiently as possible.

The trend is a return to the past. Twenty years ago, mainframes were cooled by water jackets that worked like a car's radiator, pulling heat from the engine and releasing it elsewhere. But there's resistance this time because some IT professionals don't want to reintroduce fluids to modern data centers in which temperatures are controlled by large air conditioning units. The thinking is that all those expensive servers, jam-packed with sophisticated electronics and software, are best kept dry.

Time to rethink. As data centers embrace racks of servers and closely packed blade servers, which kick off more heat per square foot than individual servers, liquids may be the only way to keep up. Says IBM's Jim Gargan, "On a warm day, do you get more relief from diving into a pool of water or sitting under a fan?"

SprayCool's chip-cooling system lives up to its name

Gargan, the VP responsible for IBM's System X cooling technology, predicts that by next year most businesses will spend more money to power and cool their data centers than they spent on the computer systems inside them. He calls data center power consumption and cooling "the IT battlefield for the next decade."

Strategies include buying servers with cooler processors, reconfiguring data center layouts to improve airflow, and moving cooling systems closer to computers. Then there are the emerging liquid-cooling technologies. They range from water jackets that surround servers to the more radical approach of spraying liquids on a server's electronic components.

ISR, a company that specializes in thermal management technology, recently introduced a commercial version of its SprayCool M-Series direct chip-cooling technology. An M-Series module attaches to a microprocessor and sprays a liquid mist onto a cold plate that surrounds the processor, removing more than half the heat. The SprayCool G-series, which has been available for several years and used mainly in government data centers, sprays nonconductive fluids directly across a server motherboard.

Emerson's Liebert and HP are preparing direct chip-cooling technologies for the commercial market. A year ago, Liebert acquired Cooligy, which developed a cooling approach that sprays chemically treated water onto a plate placed on top of a processor. The plate has 100 or more microchannels that direct coolant onto a chip's hot spots. The cooling system already is used in tens of thousands of workstations, Cooligy says.

A group inside HP called Cool Team is working on close-proximity liquid-cool systems, direct chip-cooling, and dynamic sensor control of servers and cooling systems. In January, HP introduced its first "environmentally controlled" chilled- water platform, called the Modular Cooling System, which attaches to a server rack and uses chilled water to distribute cool air across the front of the rack. Effective cooling allows more servers to be inserted into racks, which often have empty slots to avoid heat buildup.

HP has been working on a direct chip-cooling technique for several years that would use ink-jet spray heads from its printer division to distribute drops of coolant onto microprocessors. Chandrakant Patel, the HP Fellow who heads the company's Cool Team, expects new and existing cooling technologies--conventional airflow, direct attached, and chip level--to be used in combination for years to come.