October 25, 2005 3:11 PM PDT

IBM highlights Power chip power savings

SAN JOSE, Calif.--IBM's new dual-core PowerPC 970MP processor employs several features to let the chip consume less power when possible.

The 2.5GHz chip is used in Apple Computer's latest Power Mac G5 Quad machines now and will be incorporated into IBM's blade servers in the first quarter of 2006.

Power consumption, whether in desktop, mobile or server computers, is a growing concern. Indeed, Intel highlighted performance per watt as the prime new feature of a next-generation chip architecture.

The PowerPC 970MP reduces its power consumption in a number of ways, Norman Rohrer, IBM distinguished engineer, said in a speech at the Fall Processor Forum here.

One major feature is that one core can shut down if it's not needed, Rohrer said. "You can cut the power roughly in half by shutting off one of the cores," he said.

The chip also can cut its frequency by half or a quarter. Peak power consumption of 100 watts drops to about 60 watts and 40 watts with those moves, he said.

In addition, the chip can run in a low-voltage mode that further cuts power. And in a "deep nap" mode, it can cut its frequency to one sixty-fourth of the regular speed. With both cores active but deeply napping, the processor consumes 5 watts; with one, it's 3 watts.

The dual-core PowerPC 970MP is something of a return to an earlier era for IBM. Its predecessors, the PowerPC 970 and 970FX, are single-core chips, but they're based on the IBM Power4, which became the first dual-core server processor when it made its 2001 debut.

Each core of the PowerPC 970MP has its own 1MB section of high-speed cache memory. Having separate caches allows the computer to shut down one cache along with the processor core if it's not needed, Rohrer said. The 1MB cache also gives a performance boost compared with the 512KB cache used in the PowerPC 970FX.

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Not very useful for a workstation, but...
still too hot for a laptop.

So Apple's new quad core desktop uses 200W just for the CPUs when the two processors (four cores) are going full tilt. That's pretty hot.

Since workstations are designed thermally for the chips to be run as fast as possible, being able to scale back is not a huge advantage in a workstation/desktop.

The other wattages (one turned off, lower clock speed, etc.) are still mostly too high for a laptop. With one core turned off and the clock of the remaining, running cut in half it gets into a decent thermal range for a laptop, but why buy the MP when a single CPU with a single core from Freescale uses less power and is almost certainly faster? (I'm referencing a single core of the MP running at half speed or 1.25 GHz whereas the Freescale "G4" runs at 1.67 GHz.)

Sounds like IBM is just trying in vain to counter Jobs' statements this past summer about Intel having a better performance per watt future roadmap than IBM does.
Posted by shadowself (202 comments )
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Strange scaling...?
I was reading this here atricle, and they said that in 'deep nap' mode, each core can scale back to 1/64 of it's normal clock of 2.5GHz; 2½ billion cycles/sec. Now, I thought about that, and the ½ and ¼ cuts seemed alright to me. But I did a calculation, and (2½ billion/64) = (39 million/1000) = 39MHz....Which surprises me, this seems to take any of Intel's SpeedStep technology and tramples it...

Perhaps if there is a notebook version of this CPU, it could have a larger range of scale-back speeds. Perhaps larger than ¼ but smaller than ½? Maybe a number of them from the 1/64 all the way to full speed? Maybe different speeds for each core?

Can they do that? Scale one core back and have the other going full steam ahead? Interesting...I almost want one now. :(
Posted by (6 comments )
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Pretty Amazing
I know the Mac fanboyz are already kicking dirt on IBM's grave
(The Great One has spoken), but this is some facinating stuff IBM
did here, with a design that wasn't originally built for it. IBM has
a single core 970FX which they tout as their real low power chip.
Does anyone know what it specs out at?

Well, I'll say it if no one else will - IBM has been impressing me
lately. It's amazing what they can do with the a PowerPC design.
No matter how old or screwed up the commentators might claim
(ha!)

I know the G5 didn't live up to initial expectations, but it still
manages to be a premier chip - the new dual core variant is
tearin it up on the tests I heard about. What 'coulda been' if Jobs
hadn't had his hissy fit, and these two misfit companies were
still feeding off each other?

Actually, I've been wondering what this transition is all about for
Apple ever since the new G5s came out. I mean, I get it about
laptops being important and all, but aren't they selling like
hotcakes for Apple even with that pissant G4? Intel, even with
their low power rep, is really kind of a big slug these days in
overall performance compared to competitors ... I dunno, kind
of a head scratcher.

Seems like Apple may be jumping the gun here to me. More
potential with IBM. Or AMD at least.
Posted by bcsaxman (69 comments )
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Not really amazing, but cool nonetheless...
Apparently, Apple said that IBM couldn't mass produce the PPC chips in quantities that they wanted. I guesss that might be why Apple users pay a premium on Apple hardware. Plus, there aren't as many supporters of the PPC platform, so there are fewer sales because of that as well.

And according to Apple, AMD doesn't have the mass procuction capability either, even though they are finishing a brand new chip fab in Germany that will boost their production capabilites.

Intel on the other hand, has less effecient chips, can produce them like there's no tomorrow, and have a very high tag on them compared to AMD. I'm not even sure myself why they chose Intel over AMD either, but I guess since they will be using Intels better Yonah-based cores, we might see Intel come up on AMD in the desktop market.

At least that's what I've heard; Apple is planning to use Intel's Yonah platform for their desktops, which are basically upgraded Centrino-based CPUs and such. I almost want to wait and see what Apple does with OSX and Intels' chips.
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