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Frequently asked questions for Enhanced Intel SpeedStep® Technology on Desktop

Frequently asked questions for Enhanced Intel SpeedStep® Technology on Desktop

What is Enhanced Intel Speedstep® Technology?

Enhanced Intel SpeedStep® Technology allows the system to dynamically adjust processor voltage and core frequency. This can result in decreased average power consumption and decreased average heat production. By decreasing power and heat on desktop PCs, system builders can (depending on system configurations) potentially lower acoustics and even develop more innovative small form factor designs. Additionally, this feature can help address power concerns in companies with sites approaching the limits of bounded electrical infrastructures. Combined with existing power saving features, Enhanced Intel SpeedStep Technology can provide an excellent balance between providing power when you need it and conserving it when you don’t. Enhanced Intel SpeedStep Technology builds upon that architecture using design strategies that include the following:

  • Separation between voltage and frequency changes. By stepping voltage up and down in small increments separately from frequency changes, the processor is able to reduce periods of system unavailability (which occur during frequency change). Thus, the system is able to transition between voltage and frequency states more often, providing improved power/performance balance.
  • Clock partitioning and recovery. The bus clock continues running during state transition, even when the core clock and phase-locked loop are stopped, which allows logic to remain active. The core clock is also able to restart far more quickly under Enhanced Intel SpeedStep Technology than under previous architectures.

Because Enhanced Intel SpeedStep Technology reduces the latency associated with changing the voltage/frequency pair (referred to as P-state), those transitions can be practically undertaken more often, which enables more-granular demand-based switching and the optimization of the power/performance balance based on demand. This article gives developers an overview of the support for Enhanced Intel SpeedStep Technology and demand-based switching under Linux. It is also a ready reference for developers interested in new user-level or in-kernel policy based on Enhanced Intel SpeedStep Technology.

For more information on the reference material above, please refer to the complete document at the following link: Enhanced Intel SpeedStep Technology and Demand-Based Switching on Linux*

For more information on Enhanced Intel SpeedStep® Technology in general as well as for processor power and thermal specifications, please refer to the explanation provided in each processor's datasheet.

Which Intel® Processors support Enhanced Intel Speedstep® Technology?
Consult the Product Specifications and Comparisons tool to see if your specific processors support Enhanced Intel SpeedStep Technology.

Is Enhanced Intel Speedstep® Technology compatible with Intel Hyper-Threading Technology?
Yes. The operating system sees two virtual processors. Requests to change the power state are prioritized between each virtual processor by the BIOS and the operating system; the power state will default to that of the virtual processor requesting the highest state.

What are the system requirements to support Enhanced Intel Speedstep® Technology?
To take advantage of Enhanced Intel SpeedStep Technology, the CPU, chipset, motherboard, BIOS, Operating System, and software/drivers must support Enhanced Intel SpeedStep Technology.

CPU: An Intel® Desktop Processor with Enhanced Intel SpeedStep Technology support is required. Consult the Product Specifications and Comparisons to see which processors support Enhanced Intel SpeedStep Technology.

Chipset: A motherboard with one of the following chipsets is currently required to support Enhanced Intel SpeedStep Technology: Intel® 910 Express Chipset Family, Intel® 915x/925X/XE Express Chipset Family or Intel® 945x/946x/955X/975 Express Chipset Family, Intel® 965/963 Express Chipset Family, Intel® 3 Series Chipsets, Intel® 4 Series Chipsets, Intel® 5 Series Chipsets, or Intel® 6 Series Chipsets.

Motherboard: The motherboard manufacture’s system board must support Dynamic Voltage Identification (Dynamic VID). All Intel® Desktop Boards support Dynamic VID. See Intel® Desktop Boards for available Intel Desktop Boards. For all others, contact your motherboard manufacturer for specific support for Dynamic VID.

BIOS: A BIOS must have support for Enhanced Intel SpeedStep Technology. For Boxed Intel Desktop Boards, see Intel® Desktop Boards For all others, contact your motherboard manufacturer.

Operating system: An OS that supports Enhanced Intel SpeedStep Technology is required. Current supporting OSs include: Microsoft Windows Vista*, Microsoft Windows XP* SP2 and Microsoft Windows 7*. Linux* support is also available. Contact your OS vendor for more information.

Software/Drivers: No specific software or driver updates are currently required. However, it is recommended that you always have the latest drivers for your system hardware.

How do I use Enhanced Intel Speedstep® Technology?
Standard integration procedures should be followed for installing all the various system hardware components. Once all the hardware components have been installed correctly (or if the system is already functional) take the following recommended steps:

  1. If necessary, download and run the latest BIOS update for your motherboard. Check with your motherboard manufacture to ensure their latest BIOS contains support for Enhanced Intel® SpeedStep Technology
  2. Ensure Enhanced Intel SpeedStep Technology is enabled in your BIOS. If the BIOS is from American Megratrends, Inc.*, the Intel SpeedStep Technology option can be enabled in the "Advanced" tab. Ensure it is set to Enabled. For BIOS related questions, contact your system or motherboard manufacturer.
  3. Ensure your OS has support for Enhanced Intel SpeedStep Technology. For Microsoft Windows XP SP2 operating systems install Microsoft Windows XP SP2 if you haven’t already done so.
  4. Finally Enhanced Intel SpeedStep Technology must be turned on in the OS. Currently, for Microsoft Windows XP SP2 operating systems Enhanced Intel SpeedStep Technology by default is off. To turn it on do the following:
  • Under Control Panel – open Power Options
    • Under the Power Schemes pull down menu
      • To turn Enhanced Intel SpeedStep Technology ON select, “Minimal Power Management,” power scheme.
      • To turn Enhanced Intel SpeedStep Technology OFF select, “Always On,” power scheme.

To verify that Enhanced Intel SpeedStep Technology is enabled do the following:

  1. Close all applications and ensure that Microsoft Windows* OS is in idle mode.
    • Press Ctrl + Alt + Delete and select the Performance tab. Verify that CPU usage is 0%.
  2. Right click My Computer and select “Properties
  3. Under the General tab examine the installed processor and speed. If Enhanced Intel SpeedStep Technology is enabled, two processor speeds will be listed. The first speed listed is the specified speed of the processor. The second speed is the current operating speed. The second speed will be less than the 1st speed. (See fig. 1) This indicates that Enhanced Intel SpeedStep Technology has effectively lowered the processor voltage and core frequency, which can (depending on system usage and design) result in decreased average power consumption and decreased average heat production. If Enhanced Intel SpeedStep Technology is off then both processor speeds will be equal. (See fig. 2) If the processor is not in idle mode, Enhanced Intel SpeedStep Technology can be enabled and both processors speeds can be equal. If this happens try steps 1-3 again

Figure 1 (EIST ON):

Figure 2 (EIST OFF):

Where can I find information such as processor speed, processor number, cache size, chipset compatibility, pricing, and product order codes?
Information about Intel® Processors can be found by searching Intel Product Information.

For more information on other processor related topics, please refer to the following:

Operating System:

OS Independent

This applies to:

Intel® Celeron® Desktop Processor
Intel® Core™ i3 Desktop Processor
Intel® Core™ i5 Desktop Processor
Intel® Core™ i7 Desktop Processor
Intel® Core™ i7 Processor Extreme Edition
Intel® Core™2 Duo Desktop Processor
Intel® Core™2 Extreme Processor
Intel® Core™2 Quad Processor
Intel® Pentium® 4 Processor Extreme Edition
Intel® Pentium® 4 Processors
Intel® Pentium® D Processor
Intel® Pentium® Processor for Desktop

Solution ID: CS-032349
Last Modified: 27-Jun-2014
Date Created: 14-Mar-2011
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