Hitachi develops water-cooling system for notebook PCs

Water-cooled processors, currently the domain of supercomputers, high-end servers and garage hobbyists, may be about to enter the mainstream. Hitachi has developed a prototype notebook PC that uses a water-based solution to cool down its Pentium 4 processor and is planning to commercialise the product for corporate users in the third quarter of this year, the company said on Tuesday.

The faster the processing speed of a chip gets, the more heat it generates, and this can cause trouble if the heat is not dissipated. On notebook PCs this is usually done with an air-cooling system that makes use of a fan bolted on top of the processor. In the prototype machine, Hitachi has adopted a water-cooling system, which the company says works more efficiently and makes less noise than a fan-based system.

Inside the prototype notebook PC, a stainless steel tube of between 1 metre and 1.5 metres in length and 2 millimetres in diameter is placed over the chips. Through the tube, 50 to 60 millilitres of a water-based solution runs at a speed of 10 millilitres per minute and absorbs the heat. In doing so, the temperature of the solution can reach 60 degrees centigrade, according to Nanako Uchiyama, a spokeswoman for Hitachi.

The hot water solution is then sent to the display part of the notebook where the heat is released. By repeating this cycle, the system cools down the chips, Uchiyama said. A water tank is placed at the back of the display panel and a pump resides in the main body of the machine, she said.

Although the water-cooling system is more efficient and less noisy, the bottlenecks to commercialisation have been that the water-based solution tends to degrade and evaporate during operation. The company improved the quality of the water solution for the prototype and also improved the quality of the stainless tube to prevent corrosion.

The system has been used for the company's supercomputers before, Uchiyama said, but improvement in the quality of the water-based cooling system was necessary before it could be applied to notebook PCs because, unlike supercomputers, customers demand that they should be maintenance free, she said.

Compared to conventional air-cooled notebook PCs, the price and the size of the water-cooled notebook PC will remain about the same. Power consumption will also be approximately equal, Uchiyama said. However, the water cooling system should have a lifecycle that is 1.7 times longer than an air-cooled system, she said.

Hitachi hopes to commercialise the product sometime between July and September for corporate users in Japan and plans to adopt the system for other products such as servers and PDPs (plasma display panels), which also generate large quantities of heat and require a lot of cooling, Uchiyama said.

The company also expects its water-cooling system to be a de facto standard throughout the industry and is currently in talks with several component manufacturers for licensing, Uchiyama said.