Processor Power Consumption Holstically

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For a low-power, cool-running processor, I would pay

Nothing more than I would for a normal processor
4
15%
1-5% more than I would for a normal processor
1
4%
6-10% more than I would for a normal processor
9
35%
11-25% more than I would for a normal processor
5
19%
25-49% more than I would for a normal processor
6
23%
50% more or greater than I would for a normal processor
1
4%
 
Total votes: 26

bengoerz
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Processor Power Consumption Holstically

Post by bengoerz » Mon Mar 22, 2004 11:07 pm

I have been thinking lately about the power consumption of processors. Obviously, this relates to heat dissipation and, therein, the silence of a PC, so I was hoping that you smart people might give me your two cents on my latest questions:

1. Why isn't a technology like Intel's "Speed Step" or AMD's "Power Now" implimented on all processors, including desktops? (For those unfamiliar with these technologies, they throttle back the processor clock when cycles are going unused. By running at a slower clock, it can consume less power.) Does anyone know how much it costs to add this feature to a processor?

2. Obviously mobile processors are designed with power consumption in mind, but why is there such a LARGE difference between the desktop and laptop market in this regard? For instance, a 3.06GHz P4 sucks a max of 81.8 watts, resulting in only 50.1792 MHz per watt. The ultra-low-voltage 900MHz Centrino processor, on the other hand, consumes just 7 watts. resulting in 128.5714 MHz per watt. That means that, cycle for cycle, the 900MHz Centrino is over 2.5 TIMES more power efficient than a P4 3.06 GHz! Why is this so drastic?

3. In processor marketing, it seems that consumers still go for the higher MHz machines if all else is equal. And while we have seen some interesting marketing campaigns (such as Cyrix and AMD both using relative designations for processor speed), little has worked to change the buying habits of the typical consumer. However, it doesn't appear that any processor produced (except perhaps Via) has made an ecological appeal. By my calculations, if the 3.06 GHz P4 were as power efficient as the 900MHz Centrino, it would consume approximately 58 watts less power at any given time. Of the 164 million computers in the United States, if one-fourth could real this savings for 8 hours per day, then an average of nearly 700 MegaWatts of continuous power could be saved. This savings represents several power plants (like these coal plants for example). So, might a sense of environmental responsibility imposed by its consumers drive a processor maker to change its design concepts?

What other forces could revolutionize the power consumption of processors, and how might they be implimented? While I myself can't justify paying hundreds of dollars for a low-power, cool-running processor, I am hoping that the market will eventually make it so I don't have to!

silvervarg
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Post by silvervarg » Tue Mar 23, 2004 4:57 am

To get the fastest possible processors we will always push close to the technology limits we have at the moment. The closer we get to the limits the more heat will be produced.
With most processors you can undervolt and underclock go get somewhat close to the mobile versions power dissipation.
It is quite easy to get half speed and only one quarter of the heat dissipation.
So the Centrino processor is not very special. Notice that all low power processors are a lot slower than the fastest normal processors.

Would you even consider buying a 900MHz processor today if it wasn't a low power processor?

Edward Ng
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Post by Edward Ng » Tue Mar 23, 2004 6:31 am

I choose 11-25% but for a different reason than just silence...

As an overclocker, I've seen, that generally speaking (not always, but usually...), the low-power/low-heat version of the same core tends to overclock higher than its desktop counterpart when set to the same voltage level. And if you want to run it at the same level, it runs cooler.

Whether or not you overclock, you can win out (Athlon XP vs. Athlon XP Mobile, for example), but yes, I'd only spend up to a 1/4 extra over the normal piece.

-Ed

bengoerz
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Post by bengoerz » Tue Mar 23, 2004 11:22 am

silvervarg wrote:To get the fastest possible processors we will always push close to the technology limits we have at the moment.
But doesn't the very existance of the Centrino fly in the face of this? While I'll grant you the fact that it isn't the fastest possible processor, it is the flagship of the current Intel line. And it does this by marketing based primarily on its low power consumption.

It seems to be that the deciding factor in all this is Intel's marketing. They have such pervasive contracts with the big computer makers that whatever direction they go is where the industry follows. Sure, AMD is an alternative, but there just aren't that many AMD systems sold as compared to Intel. So, what if Intel decided that it wanted to go the low-power, cool-running route? Suddenly, processors would tout features other than clock speed. In an extreme form, advertisers might even promote via a MHz/Watt ratio.

It went against convential wisdom with the Centrino. Why can't that be brought to the desktop?

axhind
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Post by axhind » Wed Mar 24, 2004 1:36 am

AMD has implemented this in their 64-bit line, Cool 'n Quiet. And afaik it works like a charm, reducing the clockspeed and power consumption depending on the task the cpu is performing. I don't know either why it took so long though.

Intel is a victim of its own marketing-talk. They've spent the last years by convincing people that more MHz makes a cpu better, always increasing the clockspeed of their cpu's. Remember when the P4 Williamette came out? On the same clockspeed it was outperformed by the PIII... Now they are approaching the barrier of heat dissipation with current technologies and they have to do exactly the opposite, namely stagnate (or even reduce) clockspeed and optimize its performance by other means, thus reducing power consumption and heat dissipation.

Enter Centrino. Apparently a 1,6 GHz Centrino is as fast as a 2+ GHz P4 (correct me if I'm wrong). (actually Centrino is the global name for the entire platform: chipset with wifi, cpu,.. :wink:) Now they have to fight their own past marketing, because now they have 'slower' cpu's (in clockspeed) that have an equal performance. I even heard they plan on using a rating, like AMD, instead of the actual clockspeed in the future...

But I agree with you that it's time for processormakers to put heat-dissipation and powerconsumption in favour of clockspeed. With a current high-end computer you can heat a whole room, that's insane...

silvervarg
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Post by silvervarg » Wed Mar 24, 2004 6:17 am

But doesn't the very existance of the Centrino fly in the face of this? While I'll grant you the fact that it isn't the fastest possible processor, it is the flagship of the current Intel line. And it does this by marketing based primarily on its low power consumption.
There has been a market for a long time for low power processors. The primary use is in laptops, where you need to preserve battery power and you can't fit in a huge CPU cooler.
VIA has done some remarkable job in taking a small part of the desktop PC's with the VIA C3 processor with marketing as a low power processor.
There is also an interesting market for embedded systems, where a fan might not be an option. Imagine your car stopping because the CPU fan is worn out and the CPU has now overheated while driving...

Due to the increase in heat (and noise) from desktop computers the market for low power desktop processors also grow. I didn't expect AMD or Intel to just watch when VIA is taking market shares. They just have to give the market some good option with their platform.
Still we see that "laptop/low power" processors has the speed 2-3 years behind desktop processors. The reason is that this is often the speed you can get cooled reasonably easy.

I still see that Intel is aiming both pentium-M and centrino mainly towards laptops. It would be a small shift if they started marketing these towards desktop computers as well. This would compete against Intels desktop processors, so I don't think we will see this marketing shift.

wumpus
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Post by wumpus » Wed Mar 24, 2004 6:39 am

1) Intel is moving away from mhz numbers to rate processors over the next 12 months. I can't find the article right now, but this has been confirmed from multiple sources. That seems to indicate to me, that Intel is planning new processers at LOWER clockspeeds which perform higher than existing chips. Plus it addresses the immediate Pentium-M problem, where a Pentium-M at 1.7ghz is faster than a P4 2.5ghz

2) We all knew the power dissipation problem was coming; all you have to do is plot out die size vs. wattage and extrapolate that forward. That said, it's only in the last year that it has started to become a real practical problem.

So basically, I agree with you, the time for lower power usage on the desktop has come (eg Cool & Quiet). I really couldn't see it happening any sooner than this though.

bengoerz
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So corrected

Post by bengoerz » Wed Mar 24, 2004 8:39 am

Wow! I didn't know about the new Cool N' Quiet technology. I stand corrected!

I found a good overview at http://www.xbitlabs.com/articles/cpu/di ... 200_3.html.

Seal
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Post by Seal » Wed Mar 24, 2004 5:48 pm

11-25% extra i would pay... and infact i did, bought myself a mobile barton 2500+. Cooler, less power consumption and therefore quieter too.

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