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#1061
I don't know about that one but...
The overall purpose of power management is to manage the system's inactivates - that is power down things when not in use or low activity. Once those items are needed, power management is disengaged so to speak.
And actually I should have clarified the purpose of C1E/EIST which is actually related to Intel's CPU's. In short, it's an Intel CPU power saving mode, not a system power saving mode -
Source: Maximum PC Essentials: Ultimate BIOS Tweaking Guide - Page 3 | Maximum PCWhat you might not know is the purpose of some of the more obscure CPU-related BIOS settings. Both C1E and EIST relate to power-saving techniques employed by Intel CPUs. EIST, or Enhanced Intel SpeedStep Technology, is an offshoot of the notebook SpeedStep feature that lowers the CPU speed when it’s not under heavy use. C1E is an enhanced halt state that cuts the clock multiplier in the CPU to a preset value when the OS tells the chip that it has no work for it. Each has pros and cons. EIST is known for greater granularity, ramping up and down depending on load, but it does require driver support in the OS to manage it. Critics say EIST can actually reduce performance since it’s designed to operate the CPU at lower speeds whenever it’s not running at 100 percent capacity. The C1E state is issued by the OS when it’s idle, so C1E doesn’t require quite as much management. But some overclockers prefer to disable C1E since it can interfere with overclocks. We’ve seen older boards feature settings for both, but in our experience, newer chipsets from Intel contain settings only for C1E. Flipping off the features will force the CPU to always run at its maximum clock speed. Phenoms have similar features with Cool’n’Quiet (akin to EIST) and now C1E support. While you’re not supposed to, we’ve run with both settings on without issues, but your mileage may vary
You can see a perfect example of this by disabling/enabling C1E/EIST in the BIOS and than using CPU-Z check the activity of the CPU. You'll notice the CPU running at full bore with it disabled, and Idle when enabled. This of course is provided you have the proper power management set up. particularly Processor Power Management Plan....
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