Intel's Next CPU To Include Dedicated 'Power Control Unit' to Save Power

Intel Nehalem PCU image

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).

Intel Nehalem CPU photo

Technology Review:

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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More on Intel's i7 PCU
Anandtech: New Stuff: Power Management
Intel's Power Play