O.T. But interesting reading.
Cooling technologies
Running a temperature
If you think laptops run hot now, just wait ten years. Unless new technologies cool things down, you'll be able to cook on them.
By Lee Bruno
February 12, 2003
In the summer of 1986, Don Tilton was knee-deep in his fellowship at the prestigious Air Force Office of Scientific Research in Dayton, Ohio, a research center with a long history of developing cutting-edge aerospace and defense technology. Three years earlier, President Ronald Reagan had delivered his famous "Star Wars" speech in which he outlined the urgent need for a protective shield against the "evil empire's" nuclear missiles. His vision was to deploy satellites armed with, among other things, powerful lasers that could destroy an intercontinental ballistic missile in midflight. While much of the defense industry was concerned with how to build such large, destructive lasers, a few scientists, including the affable Mr. Tilton, were thinking about an ancillary but important problem: even if they could build the lasers, they needed to figure out how to cool the electronic components, since the standard fan-cooling method doesn't work in space.
Little did Mr. Tilton know that the issue of cooling would occupy him for the next 16 years and become one of the most critical problems facing the semiconductor industry. Heat, it turns out, is one of the major roadblocks in the continued march of Moore's law, which has driven the technology sector for nearly 40 years (see "Forget Moore's Law" ).
The 55 million transistors packed on an average Pentium chip (about the size of a fingernail) switch on and off at such a rapid rate that they generate too much heat for their own good. A typical laptop with a Pentium 4 processor gets hot enough to burn human skin (or at least discourage users from working in shorts). By the end of the decade, it is estimated that a square centimeter of microprocessors (a bit smaller than a postage stamp) will produce an amount of heat equivalent to the space shuttle's rocket exhaust--roughly 1,000 degrees Fahrenheit. Ouch! And as Pat Gelsinger, Intel's chief technology officer, said at an Intel developers conference last spring, "People are not going to carry rocket nozzles on their laptops." Nor do they want to listen to the large, powerful fans that would be needed to cool these chips--fans that would generate 85 decibels, almost loud enough to damage the ear drum. With so much heat and noise packed in such a small place, "it looks like there is a train wreck coming in the industry," says Dave Corbin, CEO and president of Cooligy, a stealth startup that is developing a new cooling technology for semiconductors.
The Heat Is On
But we don't have to wait ten years for the problems to arise. On May 11, 2000, Intel (NASDAQ: INTC) announced a recall of 1 million faulty motherboards, a PC's main circuit board, because the ultrafast Pentium microprocessors were reported to be overheating. As a result, PCs were either freezing up or shutting down and losing data. In response to the news, Intel stock plummeted 9.3 percent in one day of trading. Even Intel's latest chip, the Itanium, presented major cooling challenges that pushed back its release date. In 1999, Sun Microsystems (NASDAQ: SUNW) experienced a similar problem before the m_quote_type=name&view=release of one of its server systems. Those problems, never publicly discussed, forced Sun to delay the release.
Chip engineers say that 70 percent of chip failures are caused by excess heat, which results in device breakdowns, wasted time, and even lost data. For every 10-degree rise in temperature, say the experts, the reliability of the chip drops by a factor of two.
Despite these problems, chip manufacturers like Advanced Micro Devices, Hewlett-Packard, IBM, Intel, and Sun are just starting to get their hands around the issue. Transmeta (NASDAQ: TMTA), a small, yet prominent chip maker, designed its Crusoe chip with special software to reduce its clock rate (the number of times a chip switches on and off), thus reducing heat output. Other newcomers are getting into the act as well: researchers at companies like Active Cool, Cooligy, Cool Chips, and Isothermal Systems Research are placing a high priority on designing and developing chip-cooling technologies and materials.
Chillin' Out
One of those researchers is Mr. Tilton, who, with the help of an initial federal Small Business Innovation Research Award of $50,000, has continued the work he started back in the '80s. He is working on a technology in which a noncorrosive liquid is sprayed directly onto the hot electronic components. The liquid immediately evaporates, carrying away heat in the process. In 1988, he founded Isothermal Systems Research. In May 2001 it completed a $1.5 million first round of funding, led by Raven Ventures in Spokane. ISR now has around 100 employees and has generated about $12 million in revenue for 2002.
ISR's system uses a series of nozzles to spray a fine mist of fluid onto the microprocessor and its surrounding components. The resulting vapor is captured by an exchanger that dissipates the heat into the air and condenses the vapor back to a liquid. A miniature pump then recirculates the liquid. (HP is employing its patented inkjet nozzles in a similar spray-cooling technology.) ISR's technology has demonstrated the ability to cool 300 watts per square centimeter, which is roughly ten times more efficient than the forced-air cooling system that chills Intel's latest Itanium chip.
The company's spray-cooling technology, still limited in its commercial applications, is maintaining temperatures in high-end supercomputers, aircraft electronics, and microprocessors used in the U.S. Marine Corps' Advanced Amphibious Assault Vehicles, which have to operate in extreme environments, like deserts that reach 142 degrees Fahrenheit.
While chip industry experts concede that liquid cooling is effective, they question the reliability of the pumps and seals in its closed system. They also question the high cost. Mr. Tilton maintains that, once spray-cooling systems are mass-produced, economies of scale will help lower the cost. (Today, most of ISR's cooling systems are custom built, which makes their cost much higher than the few hundred dollars that chip manufacturers are willing to pay per unit.) Moreover, spray-cooling systems allow chips to run hotter and generate more clock cycles, thereby improving performance and productivity, which, in essence, offsets the higher cost of spray cooling. "Our costs get cheaper as the power density increases," says Mr. Tilton.
In the early '80s, a couple of thousand miles from Mr. Tilton's work at the Office of Scientific Research, Stanford University professor R. Fabian Pease was also immersed in cooling. His work centered around carving miniature channels along the microprocessor. Like a car radiator, these channels were filled with a special fluid that carried heat away. More than a decade passed. The Star Wars initiative stalled and transistors were not dense enough to produce heat problems. Then, in 1998, as the number of transistors began to reach a critical point and heat became a factor, a group of mechanical engineers at Stanford--with funding from the Defense Advanced Research Projects Agency (the venture capital/research arm of the U.S. Department of Defense), AMD, Apple Computer, and Intel--took up Mr. Pease's work. The team, led by Tom Kenny, designed and built a tiny silicon pump, powered by changes in electricity and pressure, that could propel the cooling fluid through microchannels roughly 150 to 300 microns wide, or a little bigger than the period at the end of this sentence.
In lab tests, the system has been very effective at removing heat. What's more, engineers say, the pump pushes a much smaller volume of fluid than spray-cooling systems. Less fluid generally means more reliability. To take advantage of this new technology, Mr. Kenny's team founded Cooligy in June 2002 with a $5.4 million round of funding from Mohr, Davidow Ventures and Granite Ventures.
Running a Temperature
If, by the end of the decade, a tiny group of microprocessors will produce the exhaust heat of a rocket, imagine several billion microprocessors humming along in a data center that covers a city block. Chandrakant Patel, principal scientist in the Internet systems and storage lab at HP, and his colleagues estimate that in five years it will cost $4 million a year to cool an average data center, up from roughly $1 million today. Companies spend about 10 percent of their entire power budget just on cooling data centers. To combat this cost, HP has been developing technology around what it calls "utility computing." In this approach, computing power operates like electricity: processing power, storage, and memory are pulled from wherever it is available: if it is hot in one place, say, Arizona, the network moves its numbers-crunching to a cooler place, say, Alaska. Mr. Patel says such smart cooling could reduce electricity costs by 25 percent.
But true utility computing is years off, so HP is studying how to identify hot areas within a data center and move processing tasks to cooler areas of the center. To that end, the company has demonstrated RoboRunner, a mobile robot that looks like a laptop riding a Segway and is armed with heat sensors. RoboRunner will roam the data center on a preprogrammed course to take temperature readings that will then be sent wirelessly to a server that shifts processing power from hotter areas to cooler ones.
It remains to be seen, however, if such a remote robot will make economic sense, just as it remains to be seen if other technologies, like Mr. Tilton's, will solve one of the most difficult problems facing the semiconductor industry. Cooling ever-hotter electronics will be a tough problem to solve, but one well worth the effort. "When you run a small company, it seems like you're fighting an endless battle, and sometimes you wonder why you stick with it. But when I come back to it, I realize the physics are right," says Mr. Tilton. So right, in fact, that if something isn't done in ten years, we'll end up with a few microprocessors producing the heat of a rocket blasting off, and that's a lot of heat in such a little space.
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