Cooling Down Hot Processors

DonnaMai writes "Face it: the only scorching hot thing you want with a chip is salsa. Any other overheating is potentially counterproductive, and can be downright damaging to the microprocessor -- or other components. This article uncovers potential ways to chill the chips."

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Before the /. effect...

[Blue-Footed Boobie]

Overheated chips get doused by readers' suggestions for cooling systems Level: Introductory

Joshua Fruhlinger (pdwe@jfruh.com) Editor and Writer 02 Feb 2005

Face it: the only scorching hot thing you want with a chip is salsa. Any other overheating is potentially counterproductive, and can be downright damaging to the microprocessor -- or other components. In this Power Architecture challenge, developers warm up to the idea of how to cool down the hotter processors. From the weird to the wonderful, readers uncover potential ways to chill the chips. Somewhere, deep inside your computer is the tiny slab of silicon that makes it go. That slab in turn is built out of millions -- perhaps hundreds of millions -- of transistors. Every time one of those transistors changes state, it leaks a tiny amount of electricity; in turn, that electricity produces heat. And that heat, accumulated over millions of transistors changing state thousands of times per second, may potentially threaten your fertility (see Resources).

Dr. Claes-Goran Ostenson saw this first hand when he concluded that one of his patients had been using a laptop in the way that its name implied, became engrossed in his work, and didn't notice the burning sensation in his lap, and thus became the first victim of what has come to be known as "lapburn." Ostenson felt the incident warranted exposure in the world of medical science, so he wrote a letter to the Lancet in 2002.

It stirred a mild amount of controversy, with commentors coming down on predictable sides. Laptop manufacturers were skeptical, while spokespersons for companies that produce chip-cooling paraphenalia looked serious and nodded sagely, implying that your lap could be next. Worries about "lapburn" spawned a whole industry of fan-based gadgets that plugged into the bottom of laptops, sometimes rendering the laptops' portability features pointless in the process. But the situation did highlight one important fact: Chips are hot.

And that's meant not in a market-ese, "everybody's-gotta-have-one" kind of way, but in a very literal and skin-scorching way.

The winner The First Law of Thermodynamics states essentially that energy -- including heat -- can not be created or destroyed. And if you think the punishment is stiff when you break municipal, state, or federal law, just try monkeying around with thermodynamic law! Also, physicists such as Frenchman Nicolas Leonard Sadi Carnot, as far back as the 19th century, recognized that heat tends to move from hot objects to cooler objects. These two rules circumscribe the work of every engineer and tinkerer who has attempted to cool down microprocessors. Once a chip has generated heat, that heat cannot simply be eliminated or suppressed: It must be inevitably moved from the superheated chip to something cooler. Problems arise when those cooler objects are the sorts of things that react badly to steady influxes of heat, such as other components inside the computer case, or a Swede's lap.

Since not many of you (or, frankly, none of you) wrote about how to actually reduce the amount of heat coming from a chip, this article focuses instead on cooling systems. Faithful reader Daniel Griffin did define the problem succinctly, however, and thus walks off with this month's grand prize of a developerWorks t-shirt. He points out that just "cooling a small area immediately above the processor" is fruitless; it's better "to move the heat away from the die than to deal with it." It's that struggle -- getting the heat away from the delicate, but hot, innards of your PC -- that has defined the cooling battle for the past decade.

Astute readers will also note that Daniel's was the only entry this month. Come on, where's the competition? Your entries are the only thing between my box seats and "balcony rear" at the opera! Won't someone please think of the columnist?

So this time, instead of your entries, this space is devoted to the history of the chip-cooling process. This is my treat to you, but don't forget t