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

Last Reviewed: 11-Jul-2017
Article ID: 000005723

The information below can help resolve issues with laptops or notebooks and Enhanced Intel SpeedStep® Technology. For the latest information, contact your computer or mobile motherboard manufacturer.


Click or the topic for details:

What is Enhanced Intel Speedstep® Technology?Enhanced Intel SpeedStep® Technology is an advanced means of enabling very high performance while also meeting the power-conservation needs of mobile systems.
  • Separation of voltage and frequency changes. By stepping voltage up and down in small increments, the processor is able to reduce periods of system unavailability that occur frequency change. The system is then able to transition between voltage and frequency states more often, improving balance between power and performance.
  • 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.

Enhanced Intel SpeedStep Technology reduces the latency associated with changing the voltage/frequency pair, or P-state. Transitions can be undertaken more frequently, enabling more granular demand-based switching, and the optimization of the power and performance balance based on demand. Enhanced Intel SpeedStep® Technology and Demand-Based Switching on Linux* gives developers an overview of the support for Enhanced Intel SpeedStep Technology, and demand-based switching under Linux*. The article is also a ready reference for developers interested in new user-level or in-kernel policy based on Enhanced Intel SpeedStep Technology.

Resources for Enhanced Intel SpeedStep Technology, processor power, and thermal specifications:

Intel® Core™2 Duo Processors and Intel® Core™2 Extreme Processors for platforms based on Mobile Intel® 965 Express Chipset Family Datasheet
Intel® Core™2 Duo Processor for Intel® Centrino® Duo Processor Technology based on Mobile Intel® 945 Express Chipset Family Datasheet
Intel® Core™ Duo Processor and Intel® Core™ Solo Processor on 65 nm process datasheet
Intel® Pentium® Dual-Core Desktop Processor for mobile datasheet
Intel® Pentium® M Processor with 2-MB L2 Cache and 533-MHz front side bus datasheet
Intel® Pentium® M Processor on 90 nm Process with 2-MB L2 Cache datasheet
Intel® Pentium® M Processor datasheet

Requirements and compatibility

Which Intel® Processors support Enhanced Intel Speedstep® Technology?See the product specifications and comparisons tool.
What are the system requirements to support Enhanced Intel Speedstep® Technology?
CPU See product specifications and comparisons.
Chipset Mobile Intel® 910GML, 915GM, 915GMS, 915PM, 940GML,943GML, 945GM, 945GMS, and 945PM
Motherboard Contact your system manufacturer to find out if the mobile motherboard in your system has a chipset that supports Enhanced Intel SpeedStep Technology.
BIOS Contact your system or motherboard manufacturer.
Operating system

Supported OS include:

  • Microsoft Windows Vista*, Microsoft Windows XP SP2*, and Windows 7*. Microsoft Windows XP SP2 and all versions of Windows 7 include native support for Intel Enhanced Intel SpeedStep Technology.
  • With Mac OS* X 10.4., Enhanced Intel SpeedStep Technology is built into the kernel and is already enabled. It cannot be controlled in the System Preference through Energy Saver.
  • Linux* support is available. Contact your OS vendor for more information.
Software/driver No specific software or driver updates are currently required. However, always use the latest drivers for your system hardware.
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 defaults to the virtual processor requesting the highest state.

Use and performance

How do I use Enhanced Intel Speedstep® Technology?Follow the standard integration procedures for installing the various system hardware components. If you are using Microsoft Windows XP*, install the Windows XP SP2*. Make sure you have met all system requirements. Once all hardware and software have been installed, use following steps:
  1. If necessary, download and run the latest BIOS update for your motherboard.
  2. Enable Enhanced Intel SpeedStep Technology in the BIOS. If the BIOS is from American Megatrends, Inc.*, under the Advanced tab, set to Enabled.
  3. Turn Enhanced Intel SpeedStep Technology on in the OS. For Microsoft Windows XP SP2 operating systems, the default setting is off. To turn it on:
    1. Click Control Panel > Power Options.
    2. Under the Power Schemes drop down menu, select Minimal Power Management.
Note 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.
    1. Press Ctrl + Alt + Delete and select the Performance tab. Verify that CPU usage is 0%.
  2. Right-click My Computer and select Properties.

Under the General tab, look at the installed processor speed. If Enhanced Intel SpeedStep Technology is enabled, two processor speeds are listed. The first speed lists the specified speed of the processor. The second speed is the current operating speed. If both processors list the same speed, repeat steps 1-3. Make sure the OS is in idle mode and CPU usage is 0%.

How do I determine if Enhanced Intel SpeedStep® Technology is working with Microsoft Windows* XP?
  1. Determine if the Enhanced Intel SpeedStep® Technology driver is working properly. Use the Intel® Processor Identification Utility. The utility shows the Intel® Mobile Processor installed, and whether it supports Enhanced Intel SpeedStep® Technology.
  2. See if the frequency changes. Run the utility while plugged into an AC outlet, then run the utility drawing power from the battery.

When powered by a battery, the processor drops to a lower frequency and voltage, conserving battery life while maintaining a high level of performance. Manual override lets you boost the frequency, allowing you to customize performance when powered by a battery.

Different from the previous versions of Microsoft Windows*, the Enhanced Intel SpeedStep® Technology driver is built into Microsoft Windows XP*. With the built-in driver, you don't have an icon in the system tray of the taskbar, nor the power applet located in the Control Panel. Determining if Enhanced Intel SpeedStep technology is operating correctly is difficult without the icon and applet.

Why does the operating speed not change on my laptop, when I go from AC to DC power, or DC to AC power?

Check the following:

  • Your processor and operating system supports Enhanced Intel SpeedStep® Technology. See system requirements.
  • Enhanced Intel SpeedStep Technology driver is loaded. The driver is only available from the laptop manufacturer or vendor.
    Note Microsoft Windows* XP automatically includes the drivers.
  • Enhanced Intel SpeedStep Technology is not disabled in the CMOS setup program (BIOS).
  • Check the settings in the Power applet in the Control Panel.
  • Check with your system manufacturer to see if they recommend updating the BIOS.
Why does my keyboard not work when I switch performance modes?You need to update your keyboard BIOS. Updates are typically available on the laptop manufacturer's website. Contact the manufacturer for more information.

For laptops running operating systems older than Microsoft Windows XP

Why did the applet icon disappear from the task bar after I changed the power management settings?In BIOS under the Power menu, make sure that your Power Savings are set to customized or automatic. You can also access the applet through the Control Panel:
  1. Select the Power Management icon.
  2. Click the Enhanced Intel SpeedStep Technology tab.

Check to see if the Enhanced Intel SpeedStep Technology icon is enabled. To re-enable the taskbar icon, click Advanced and clear the check box for Remove icon from taskbar. Click OK.

Why did the settings remain unchanged after I changed the power management settings in the applet?This may be a BIOS issue. Contact your laptop manufacturer and request a system BIOS upgrade. Laptop manufacturers generally provide downloadable updated drivers.
Why does the applet icon not appear in the task bar?This may be a BIOS issue. Contact your laptop manufacturer and request a system BIOS update. Laptop manufacturers generally provide downloadable updated drivers.
Once I remove the Enhanced Intel SpeedStep® Technology applet icon from the taskbar, how do I access the applet or bring back the icon?You can always access the applet through the Control Panel.
  1. Select the Power Management icon.
  2. Click the Enhanced Intel SpeedStep Technology tab.

To re-enable the Enhanced Intel SpeedStep Technology taskbar icon:
  1. Click Advanced and clear the checkbox for Remove icon from taskbar.
  2. Click OK.


Related topics
Intel® Processor support
Product specifications and comparisons
Intel® Processor numbers
Mobile performance
Intel® Virtualization Technology
Intel® Processor Identification Utility