Enhanced Intel SpeedstepĀ® Technology (EIST)

Posted on 25th Jul 2011 @ 1:39 AM

This document is intended only as a guide to resolve various issues with laptops and/or notebooks and Intel SpeedStep® Technology. Ultimately, your laptop/notebook system manufacturer or mobile motherboard manufacturer may have the very latest information to help resolve your issues.

What is Enhanced Intel Speedstep® Technology (EIST)?
Enhanced Intel SpeedStep® Technology is an advanced means of enabling very high performance while also meeting the power-conservation needs of mobile systems. Conventional Intel SpeedStep Technology switches both voltage and frequency in tandem between high and low levels in response to processor load. 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 explanation provided in each processor's datasheet:

Which Intel® processors support Enhanced Intel Speedstep® Technology?
Consult the Product Specifications and Comparisons tool to see which 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.

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 then 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 bee equal. If this happens try steps 1-3 again

How do I Determine if Enhanced Intel SpeedStep® Technology is working with Microsoft Windows* XP?
When the laptop computer is connected to the AC outlet, the new mobile PC runs the most complex business and Internet applications with speed virtually identical to a desktop system. When powered by a battery, the processor drops to a lower frequency (by changing the bus ratios) and voltage, conserving battery life while maintaining a high level of performance. Manual override lets you boost the frequency back to the high frequency when on battery, allowing you to customize performance.

Different from the previous versions of Microsoft Windows, The Intel SpeedStep® driver is built into Microsoft Windows XP. Therefore, you do not need to load the driver. Unfortunately, with the driver built into the operating system, you do not have an icon in the system tray of the taskbar and you don't have an Intel SpeedStep Technology tab when using the power applet located with the Control Panel. Without these programs, it can be difficult to determine if you have an Intel mobile processor with Intel SpeedStep Technology that is operating correctly.

To determine if the Intel SpeedStep Technology driver is working properly, you can use the 
Intel® Processor Frequency ID Utility. After installing the utility and running it, the utility should show you that you have an Intel mobile processor and that it supports Intel SpeedStep Technology. You can also then run the utility with the laptop plugged into the AC outlet and run the utility with the laptop drawing power from the battery to see the frequency change between them.

When I change from AC to DC power or DC power to AC, why is that the operating speed of my laptop computer does not change?
Here are some things you might check:

  • Make sure that you have a processor with the Intel SpeedStep® Technology.
  • Make sure that you have an operating system that supports SpeedStep Technology.
  • Make sure the 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.

  • Make sure the 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 doesn't my keyboard work when I switch performance modes.
Contact your system manufacturer and request an updated keyboard BIOS. Generally, a laptop manufacturer will have a web site containing downloadable updated drivers. If that does not work, contact your laptop manufacturer's support for assistance. 

Why did the applet icon disappear from the task bar after I changed the power management settings? (may apply to systems running operating systems older than Microsoft Windows XP)
In BIOS under the Power menu, make sure that your Power Savings are set to customized and/or automatic. In addition, You can always access the applet through the Control Panel. Select the Power Management icon, and click on the Intel SpeedStep Technology tab.

Note

you should check to see if the Intel SpeedStep Technology icon is enabled. To re-enable the Intel SpeedStep Technology taskbar icon, click on Advanced button and uncheck the "Remove icon from taskbar" box, and click OK.

Why did the settings remain unchanged after I changed the power management settings in the applet? (may apply to systems running operating systems older than Microsoft Windows XP)
This could possibly be a BIOS issue. Contact your laptop manufacturer and request a system BIOS upgrade. Generally, a laptop manufacturer will have a Web site containing downloadable updated drivers. 

I know my laptop supports Intel SpeedStep® Technology, and I have the right processor, but when I install the applet, why doesn't the applet icon appear on the task bar? (may apply to systems running operating systems older than Microsoft Windows XP)
This could possibly be a BIOS issue. Contact your laptop manufacturer and request a system BIOS update. Generally, a laptop manufacturer will have a web site containing downloadable updated drivers.

Once I remove the Intel SpeedStep® Technology applet icon from the taskbar, how do I access the applet or bring back the icon? (may apply to systems running operating systems older than Microsoft Windows XP)
You can always access the applet through the Control Panel. Select the Power Management icon, and click on the Intel SpeedStep Technology tab. To re-enable the Intel SpeedStep Technology taskbar icon, click on Advanced button and uncheck the "Remove icon from taskbar" box, and click OK.

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 the processor products database