Intel's Next CPU To Include Dedicated 'Power Control Unit' to Save Power
by Michael Graham Richard, Ottawa, Canada 
on 08.22.08
Making more Power-Efficient Computer Processors
Efficiency and power management are all the rage these days in the IT world. Novel ways of cooling data centers, virtualization and consolidation, etc. The hardware itself has also gotten better in the past few years (for example, desktop and server CPUs now have many of the features that used to be found only in laptop CPUs).
Nehalem's PCU, 1 Million Transistors
Intel has announced at the Intel Developer Forum (IDF) that i7 a.k.a. Nehalem, its next generation CPU, will include a Power Control Unti (PCU) dedicated to making the chip more efficient. About 1 million transistors, as much as a 486 CPU used, will be used for the sole purpose of managing power using temperature sensor data and software feedback (OS requests, etc).
If only two cores of a four-core machine are active, for instance, the control unit will completely shut down the inactive cores and divert spare power to active ones. The unit can also moderate the speed and power consumption of each core independently. [...]to further save power, Intel's engineers developed a way to shut off transistors when they aren't in use. "The concept is trivially obvious and has been around for decades," says Kumar, "but doing it was hard." It required developing new transistor technology to ensure that the switch had low resistance when it was on but an extremely high resistance when off.
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THis is good news. Personal computers can use the same amount of electricity as a microwave oven running continuously, although most use less. What needs to be done next is a graphics processor unit (GPU) bypass. My GPU uses 150 watts at idle. It should only be one when I'm gaming, as that's when it's special processing abilities are actually used.
I think it's interesting that the technology only seems to be applying to more powerful processors. Most applications don't require huge amounts of processing power, so I'm not sure why we can't introduce technology that exists (like in the XO Laptop) into new models of computers. Or at least encourage those who do computing to only buy processors at the level necessary for their applications. I actually just wrote an article about this on my blog.
Though of course I do agree that for power-users, having a built in power control unit will be great, and hopefully will save a good bit of power.
Josh
You're right Josh, but most people don't have any idea how that box on their desk works or how much processing power they need. They also don't realize their system's performance is as likely to be limited by the ram, hard drive, network speed, bus bandwidth, and graphics card as the CPU. It's the megahertz myth all over again, only more complicated.
Maybe it is time for a class in comp. sci. to be required for high school graduation, along with the other sciences.