How cool is that IBM supercomputer?

Some time over the next five to ten years, IBM expects to replace a new water cooling method for its Hydro-Cluster supercomputer -- just unveiled in April -- with an emerging approach based on 3D chip stacks.

Right now, IBM's new Hydro-Cluster model removes heat from processors by means of water-cooled cooper plates instead of traditional heat sinks. For instance, the Power 575 system rolled out two months ago is billed as tripling energy efficiency while also operating five times faster than IBM's earlier supercomputers.

But using its forthcoming 3D chip stack method, IBM will stack memory chips between processor cores so as to multiply interconnections 100 times over, according to researchers at IBM's Zurich Research Library.

Water will be shot through 50-micron channels between the stacked chips, with the intent of cooling the stack at the rate of 180 watts per layer.

"This compact integrated hybrid cooler uses a novel flow scheme to spread heat with a much lower thermal resistance than coolers that use solid copper or vapor chambers," according to a project overview from the Zurich team. "This novel cooler interfaces with the microprocessor chip and spreads heat over a large area, where it can be cooled using conventional fins and forced-air convection. The core exchange area directly in contact with the microprocessor chip consists of a highly optimized solid-to-liquid heat exchanger."

As one of the most challenging remaining barriers in their research, the IBM team cited "the limited spacing between chips where the heat has to be removed...The goal is to design a low-pressure drop fluid path to minimize the pumping power while being able to remove high power densities," the researchers revealed.

A full paper by the Zurich researchers about the future 3D stack cooling method took home a Best Paper award from the IEEE ITherm conference in Orlando, Florida in May.