IBM researchers find new way to cool chips

IBM researchers have found a way to draw twice as much heat off of hard-working computer chips, clearing the way for server farms and data centers to use denser, faster processors.

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The researchers discovered a better way to squeeze thermally conductive paste between hot chips and their heat sinks, the company announced Thursday at the BroadGroup Power and Cooling Summit in London.

Inspired by the natural branching patterns of tree roots and human veins, the IBM group discovered they could move a large volume of paste with very little energy, avoiding the danger of damaging or cracking chips as they expand at high temperatures.

This advance will allow engineers to design more powerful chips and continue to follow the Moore's Law trend of shrinking transistors to ever-smaller sizes, said Bruno Michel, manager of the advanced thermal packaging research group at IBM's Zurich Research Laboratory.

As chips become more dense, they are increasingly constrained by their own heat, with modern processors using up to 100 watts per square centimeter. That is already pushing the upper limit of current cooling technology, which relies on fans to blow air over heat sinks. Some large server farms need so many fans that IT managers spend as much money to cool the chips as they do to run them.

Because of that budget paradox, many computer vendors have found that cooling systems have changed from mere technical detail into great marketing pitch.

When it launched a range of blade and rack servers in August, IBM gave equal billing to their fast chips and their new cooling technique. The "Cool Blue" feature sucks heat out of racked servers by running liquid through the enclosure doors.

Likewise, Dell founder Michael Dell boasted at a trade show on Monday that his company's latest desktops and servers would use less electricity -- and produce less heat -- thanks to more efficient processors. Chip manufacturers claiming to make those more efficient, cooler processors include Advanced Micro Devices with its "Rev F" Opteron, Intel with its "Woodcrest" Xeon 5100 and future "Clovertown" quad-core Xeon and Sun Microsystems with its UltraSparc T1.

But future chips will get even hotter, so the IBM researchers have already begun testing an even better approach, cooling chips by spraying them with water instead of air. This "direct jet impingement" method uses an array of 50,000 tiny nozzles circulating water in a closed loop, protecting the delicate chips circuits from getting wet. In early results, the system has absorbed the power of 370 watts per square centimeter, about four to six times better than current air cooling methods.