IBM Developing Water Cooling for Chips

By Scott Ferguson  |  Posted 2008-06-05 Print this article Print

Big Blue claims to have developed a method using water to cool 3D chip stacks.

In the future of computing, IBM is attempting to demonstrate that water, not air, is the best way to cool the tiniest components of the data center.

At a technical conference June 5, IBM, along with researchers from the Fraunhofer Institute in Berlin, will demonstrate a new system of cooling microprocessors by piping water directly into the chip instead of the more conventional method of using air to remove heat and cool a system.

As microprocessors become smaller and smaller, and as companies such as IBM, Intel and others add more processing cores and capabilities to the next generation of chips, the amount of heat these processors produce also becomes greater. The thrust of the IBM research is to find a better way to remove heat at the chip level, which will also have an effect on the amount of power used in the data center.

To achieve this, IBM researchers are drilling tiny holes in a three-dimensional chip stack and pumping water through these pipes to cool the chip. The company first demonstrated its chip stacking technology in 2007, which places the chips and memory components on top of one another on a silicon wafer instead of side-by-side.

While innovative, these sandwiched chips-one measures about 4 centimeters square and is about 1 millimeter thick-can dissipate about 1 kilowatt of power. Instead of trying to cool the chips with air, researchers decided to pump water into the stack through pipes that measured about 50 microns or 50 millionths of a meter, which is about the thickness of a human hair.

While water might hold the key to better power efficiency, IBM also made sure to insulate the electrical components from the water that would flow through the chip, taking the heat with it as flowed out. The method that the company's researchers developed uses a thin layer of silicon oxide to insulate the electrical components.

"In the final setup, the assembled stack is placed in a silicon cooling container resembling a miniature basin," according to IBM. "The water is pumped into the container from one side and flows between the individual chip layers before exiting at the other side."

Joe Clabby, an analyst with Clabby Analytics, has done research that has shown that water is 23 times more energy efficient than air in terms of heat dissipation. This means that water is not only more efficient than air at removing heat, it's also faster and reduces overall power consumption by eliminating the need for more air conditioning to cool the servers that use these chips.

"The enterprise computing world has got to move to water," said Clabby. "If you're building an enterprise data center, you're going to make it very dense and you're going to make it very energy efficient. The reason you are moving to this water cooling idea is not only are you able to remove heat more efficiently, but you don't have to cool air using air conditioning."

Water cooling harks back to the days of the mainframe computer. However, as smaller computers were developed, Clabby said designers turned to air. But the trend now seems to be moving back to water to solve the heat and cooling issues.

A drawback to this type of water-cooled system, Clabby said, is the price of investing in an entirely new infrastructure. What IBM has to do in the commercial market is prove that the cost of buying this type of hardware will be offset by reductions in energy use and cooling costs.

IBM did not indicate when it would bring this type of chip-cooling technology into the market, although the company did use existing fabrications methods to build the prototype, which means the technology is destined for the commercial market.

In April, IBM announced that it had developed new water-cooling methods for its Power 575 supercomputer. This machine had been designed with a grid overlay, with water-chilled copper plates placed above each processor. This cooling system absorbs the heat and then removes the water and heat from the rack. The first of these systems is being installed at the National Center for Atmospheric Research facility in Colorado.


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