Frequently Asked Questions about Enhanced Intel SpeedStep® Technology for Intel® Processors


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What is Enhanced Intel Speedstep® Technology?

Enhanced Intel SpeedStep® Technology allows the system to dynamically adjust processor voltage and core frequency, decreasing average power consumption and heat production.

By decreasing power and heat on desktop PCs, system builders can potentially lower acoustics, depending on system configurations. They can also develop more innovative small form factor designs.

The feature also helps 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 balance between power production and consumption. It uses design strategies that include the following: 

  • Separation between voltage and frequency changes. Stepping voltage up and down in small increments separately from frequency changes allows the processor to reduce periods of system unavailability (which occur during frequency change). The system can 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, when the core clock and phase-locked loop are stopped. Logic remains active. The core clock can also restart 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 undertaken more often. More-granular, demand-based switching and optimization of the power/performance balance is enabled.

For an overview of support available, see the enhanced Intel SpeedStep Technology and demand-based switching on Linux*. The resource is a ready reference for developers interested in new user-level or in-kernel policy based on Enhanced Intel SpeedStep Technology.

For more information on Enhanced Intel SpeedStep® Technology, processor power, and thermal specifications, refer to processor datasheets.

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?

The CPU, chipset, motherboard, BIOS, Operating System, and software/drivers must support Enhanced Intel SpeedStep Technology.

  • CPU:
    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 required to support Enhanced Intel SpeedStep Technology: Intel® 910 / 915x / 925X / XE Express Chipset Family or Intel® 945x / 946x / 955X / 975 / 965 / 963 Express Chipset Family, Intel® 3 Series Chipsets, Intel® 4 Series Chipsets, Intel® 5 Series Chipsets, or Intel® 6 Series Chipsets.
  • Motherboard:
    The system board must support Dynamic Voltage Identification (Dynamic VID). All Intel® Desktop Boards support Dynamic VID. For all others, contact your motherboard manufacturer for specific Dynamic VID support.
  • BIOS:
    A BIOS must support Enhanced Intel SpeedStep Technology. For Boxed Intel® Desktop Boards, see Intel® Desktop Boards For all others, contact your motherboard manufacturer.
  • Operating system:
    An OS must support Enhanced Intel SpeedStep Technology. Current supporting operating systems 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, we recommend 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 system hardware components. Once all hardware components have been installed correctly (or if the system is already functional), use the following steps:

  1. If necessary, download and run the latest BIOS update for your motherboard. Check with the motherboard manufacturer to ensure the latest BIOS supports Enhanced Intel® SpeedStep Technology.
  2. Ensure Enhanced Intel SpeedStep Technology is enabled in your BIOS. If the BIOS is from American Megatrends, 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 supports Enhanced Intel SpeedStep Technology. For Microsoft Windows XP SP2 operating systems, install Microsoft Windows XP SP2 if you haven’t already.
  4. Turn on Enhanced Intel SpeedStep Technology in the OS. Currently, for Microsoft Windows XP SP2*, Enhanced Intel SpeedStep Technology is off by default.
    To turn it on:
  • 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:

  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, see 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 lower than the 1st speed (see Figure 1). A lower second speed indicates that Enhanced Intel SpeedStep Technology has effectively lowered the processor voltage and core frequency. Depending on system usage and design, lowered frequency can decrease average power consumption and heat production.

    If Enhanced Intel SpeedStep Technology is off, then both processor speeds will be equal (see Figure 2). If the processor is not in idle mode, Enhanced Intel SpeedStep Technology can be enabled and both processors speeds can be equal. Try steps 1–3 again.

Figure 1 (EIST ON):

Figure 2 (EIST OFF):

EIST on EIST off
Where can I find processor speed, number, cache size, chipset compatibility, pricing, and product order code information?

See Intel® Product Information.

Related topics
Intel® Processor support
Product specifications and comparisons
Intel® Processor numbers
Virtualization Technology
Intel® Processor Identification Utility
Performance benchmarks