Power consumption...

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From: Zhang, Yangkun (Yangkun.Zhang@FMR.COM)
Date: Mon Oct 23 2000 - 07:07:33 PDT

Follow up to the Gilder article I posted last week...


Burn Rate
Peter Huber, Forbes Magazine, 10.30.00

CHIP ENGINEERS LIKE TO BOAST THAT IF DETROIT had improved its own technology
as fast as theirs, your Buick would now go 10,000 mph and cover 2,000 miles
on a gallon of gas. And it's true. They neglect to add that you'd also be
driving to the moon and back every month, and using 180 gallons of gas to do
so. The microchip proves yet again that technology scoffs at every limit to
growth--so long as you supply it with unlimited energy. And we're burning
more and more of the stuff to keep our silicon hot.

Bell Labs engineer Kaveh Azar sets out the numbers in a recent paper in
Electronics Cooling. Chip efficiencies have indeed improved at a remarkable
pace. The number of gates on the Intel processor has doubled every 18 months
or so. The amount of power consumed by the chip has increased exponentially,
too, albeit at a slower--roughly 36-month--doubling rate. Memory, video
chips and even chips optimized for power-conscious laptops have all been
riding up similar power curves.

How come? Within the chip itself, the electrical energy required to process
a single instruction has been cut in half about every 14 months as the
average size of the individual gate has shrunk. But the number of gates per
chip and the chip's clock speed have risen at the same time. Overall, the
number of bits processed has risen much faster than "bit efficiencies" have

And the chips themselves are, of course, multiplying across the continent
like locusts. Rising energy densities in the individual microprocessor are
mirrored in other chips on the motherboard and in adjacent desktop
peripherals, through backup power supplies, network cards, modems, telephone
switches, routers, wireless links, lasers, caching systems, servers and the
chip fabs themselves. As a colleague and I outlined in these pages over a
year ago ("Dig More Coal--the PCs Are Coming," May 31, 1999), the electrical
loads add up to big numbers when you track them across the digital

So the efficiency paradox bites us again: more efficiency, more consumption,
too, because better performance and lower effective price outweigh
everything else. The Eniac computer of 1946 was an enormous beast, with
18,000 vacuum tubes that consumed 180,000 watts of electrical power. Today
you can find 2,000 times as much computing power in a 5-watt Nintendo 64. If
your refrigerator had made as much progress down the energy curve, it would
now be powered by a hearing-aid battery. But one Nintendo per teenager adds
up to a whole lot more demand for electric power, overall, than one Eniac
per planet.

And better power, too. The faster the chip, the more exacting its demands
for power quality. For a chip clocked at 1 gigahertz, a blackout is any
interruption that lasts more than a billionth of a second. A huge new power
infrastructure is growing up around the silicon, from tiny capacitors on the
circuit board to megawatt-scale backup turbines that keep "server hotels"
hot when the public grid fails. In digital circles the big power investments
aren't in the extra kilowatt-hours, expensive though they are; they're in
the fancy hardware that keeps the electrons reliable.

Back at the chip level, engineers now foresee energy densities at the
surface of the silicon approaching those in the core of a nuclear reactor.
And thermal problems now present (along with physical limits to
photolithography) one of the largest obstacles to further miniaturization.
The gates keep shrinking, all right, and there are ways to pump in the watts
they require; but what goes in as power comes out as heat, and at some point
the silicon begins to melt. Microprocessors are now sprouting big cooling
fins; some even come equipped with water-cooled microradiators. Money and
research talent are being poured into finding better materials and
architectures to cool the digital brain.

Peter Huber (pwhuber@bellatlantic.net), a Manhattan Institute fellow, is the
author of Hard Green: Saving the Environment from the Environmentalists and
the Digital Power Report. Find past columns at www.forbes.com/huber.

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