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Not many of us could convince our bosses that we’re most efficient when working slowly. But then, we aren’t microprocessors. For decades, researchers have known that processors achieve peak energy efficiency when their transistors operate at very low voltages near the threshold between their on and off states. Unfortunately, the circuits also become unstable at those low voltages. Nevertheless, Intel is trying to apply that research to future products.
The technology is called near-threshold voltage (NTV) computing. In effect, it’s extreme underclocking. PC users are more familiar with overclocking—cranking up the processor’s clock frequency and/or voltage to squeeze out more performance. Although overclocking works, it consumes more power—a small price to pay when we’re hungry for speed.
However, the price isn’t always small. Big data centers are sometimes limited by the electrical grid’s local capacity, and their cooling often gobbles more power than the servers do. At the other end of the spectrum, mobile devices must save energy to lengthen battery life and to keep from becoming too hot to handle.
Today’s processors can’t operate much below 1.0V. Intel has an experimental x86 processor (Claremont) rumored to work at 0.6–0.7V. Although that difference may seem tiny, it’s actually huge. Intel says the chip remains fully active (not in sleep mode) while sipping less than 10 milliwatts—low enough to run on a small solar cell.
The sacrifice is raw performance. Clock speed drops dramatically, but power efficiency (performance per watt) is five times higher. When more performance is needed, boosting the voltage drives the processor to its full clock speed.
Future processors could run some or all CPU cores at NTV levels most of the time. Stabilizing the circuits requires fine-tuning, though. With its own fabs, Intel has a potential advantage over competitors that outsource manufacturing to independent foundries.
Comments are closed on this article
LatiosXT
November 16, 2011 at 9:33am
As everyone said, this is more or less useful for the mobile environment, where mobility means how long you can stay off the grid, not how much performance you can get out of a machine.
Well, of course, it also helps if the processor can still perform its tasks within a reasonable time.
Sovereign
November 16, 2011 at 7:45am
I see a lot of comments angling at "who cares about saving energy rarrrrr." I think that's missing the point--at least for mobile devices. Battery life on modern devices could be better, and this will help us get there.
Also, extreme power gating on desktop CPUs could supercharge Intel's already impressive Turbo technology.
vonhulio
November 16, 2011 at 5:58am
I both undervolt AND underclock my smartphone. With a simple undervolt of 50-75mv and an underclock from 1ghz down to 700mhz, you can easilly achieve 8 hrs of extra battery life. It makes all the difference in the world on long work days, out on the road without the ability to charge. I can also honestly say that I am unable to differentiate any change in speed with the changes applied.
yr
November 15, 2011 at 9:21pm
I agree that the little savings in power is not worth the massive effort. But there are 3 HUGE benefits:
1) Battery life could increase when doing non-intensive things, like browsing the web or reading mail. Batterys could last almost twice as long!
2) Solar powered cell-phone / tablet / laptop? If it won't use more energy than a solar panel can produce, you could use it all day with little or no battery drain, and even have a charged battery for after-dark use.
3) PC's and Datacenters generate lots of HEAT. Lower powered cpu's make less heat, and require less cooling. Media center PC's could be smaller and even left in closets with minimal venting. Servers wouldn't need as many air conditioners. Desktops won't heat up the room when not doing heavy use.
I say BRING IT ON.
oldobamaliar
November 15, 2011 at 4:25pm
what are we talking about 50 cents per month for the average user?
Blaze589
November 15, 2011 at 3:54pm
I sometimes underclock my desktop CPU to 60% (.975v @ 880MHz) via a custom power saving plan in Windows 7 when I plan on leaving my PC for 4-6 hours or more if I'm seeding torrents or doing other tasks that don't require much CPU power. For the most part the dynamic clock of contemporary CPUs is good enough for everyday use.
davidtuerk
November 15, 2011 at 2:48pm
im 14 I dont really care about my processor using 124 watts. but it does add up and cost I know. But Im never going to underclock my cpu to save on power
SAND_CREATURE
November 15, 2011 at 2:21pm
I would never underclock, but undervolting can still offer the same benefits without performance lost, basically inverse overclocking
I was able to take a laptop of mine down from .9 volts to .725 volts, pretty good savints
biggiebob12345
November 15, 2011 at 1:37pm
You'll never convince me to underclock my computer to save energy. Servers, sure. Desktop, hell to the freaking no. I'd be willing to double my power bill if it meant a 50% speed boost.
MrBlueCheese
November 15, 2011 at 2:20pm
I'm not sure everyone would be willing to double the power bill (depending on where they live).
I'm curious, how much different is underclocking then overclocking a CPU?
