EIST (Enhanced Intel SpeedStep Technology) Explained

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What is EIST (Enhanced Intel SpeedStep Technology)

What is EIST (Enhanced Intel SpeedStep Technology)?

Enhanced Intel SpeedStep Technology or EIST is available in the core branded CPUs which allows them to run at a slower speed in order to lower the overall power consumption.

Technically, EIST is the power management technology which also translates into thermal management.

It was developed by Intel with an intention to meet the power saving needs of the smaller portable computer systems.

KEY TAKEAWAYS

  • Enhanced Intel SpeedStep Technology helps in adjusting the voltage of the CPU along with its core frequency dynamically.
  • This specific technology allows the operating system of the computer to select and have a better control over the P-states or operating points.
  • EIST is a very useful feature for portable devices because it enhances the battery power quite significantly.
  • The technology also reduces the transition latency between the P-states, which, in turn, offers a significantly large number of transitions per second.
  • Better and glitch-free transitions are ensured by EIST because it allows the CPU to have a better control over the internal voltage ramp rates.

Understanding EIST (Enhanced Intel SpeedStep Technology)

Understanding EIST (Enhanced Intel SpeedStep Technology)

EIST is the technology available on core branded CPUs which essentially throttles their clock speed during those times when the demand is minimal.

The clock speed is brought back up to the maximum potential as and when the load and demand rise.

Intel has been using this feature since Pentium III and it typically offers two specific benefits such as:

  • It lowers the overall power consumption, and, as a result
  • It reduces heat production.

When both these aspects are diminished, the system designers can focus more on the other particular aspects such as a smaller form factor, possibly lower acoustics, and more.

Intel EIST simply allows making dynamic adjustments in the clock speed of the CPU and its voltage based on the present computing needs.

It is typically a power-saving feature that allows the software to control the cores of the processor and its speed.

Typically, this innovative technology comes with some key features that make it so useful. These are:

  • Multiple voltage points and frequency which allows the CPU to perform at an optimal level
  • Software controlled frequency selection by writing to model-specific CPU registers or MSRs which optimize voltage according to the number of IA cores in the active processors and the selected frequency
  • Locking of the Phase Locked Loop or PLL when the voltage is established onto the target frequency
  • Sharing the same voltage and frequency by the IA cores of the active processor
  • Ability to select the P-state of the highest frequency requested among the IA cores in a multi-core processor
  • Voltage ramp rates controlled by the processor internally which allows for better and smoother transitions
  • Acceptance of software-requested transitions at any time
  • Deferring a new transition if an earlier transition is in progress till the time it is completed and
  • Higher number of transitions per second due to the lower transition latency between the P-states.
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Typically, in the non-enhanced version of SpeedStep technology earlier, voltage and frequency were switched between high and low levels based on the response of the processor to the current load.

EIST is compatible with a wide range of operating systems such as:

  • The Linux kernel with a subsystem called “cpufreq” and its newer versions
  • Older versions of Microsoft Windows 2000 and earlier with a dashboard application and special driver
  • Newer versions of Windows 10
  • Microsoft Windows XP within its power management console and
  • OpenSolaris SXDE 9/07 and others.

In short, using EIST will ensure that the users are able to find the right balance between performance and power conservation which suits them the best.

They can even change the clock speed of the processor dynamically as the burden varies.

What is EIST (Enhanced Intel SpeedStep Technology)

What Does EIST Do?

What EIST actually does is drop the usual multiplier down to an x14 multiplier which reduces the clock speed but, at the same time, allows the system to lower the voltage of it automatically.

This function of the EIST, in turn, reduces the power consumption by the process or when it is idle, and as a result, it reduces the operating temperature as well.

However, when the CPU is used again, the technology will raise the voltage as well as the multiplier back up to its usual value.

The FSB or Front Side Bus, however, does not change throughout and therefore the user will lose on any bandwidth.

The Enhanced Intel SpeedStep Technology is built on a unique concept and uses much better and more useful strategies as follows:

  • Separation of voltage and frequency changes where voltage changes, up or down, are made in small increments discretely from changes in the frequency
  • Reduced system unavailability due to these changes in the processor and the ability of the system to switch between frequency and voltage states more often, which, in turn, improves the performance to power balance
  • Clock partition and recovery while the bus clock operates continuously, even in state transitions, or when the PLL and core clock are stopped, which allows the logic to continue to be active even when some of the portions of the CPU are presently not working and
  • Reduced inherent latency due to the changes in the frequency-voltage pair or P-states which ensure more frequent transitions to happen.
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All these strategies allow the CPU to perform at a more granular level with proper and quick switching based on the current demand.

This eventually optimizes the balance between power and performance, once again, based on the current demands.

In simple words, the Enhanced Intel SpeedStep Technology ensures that the CPU operates at a higher frequency and voltage at higher workloads and at lower voltage and frequencies during lighter loads.

Should You Enable EIST?

Yes, it is quite reasonable to enable EIST for both overclocking and default settings. However, you should make sure that all the hardware and software such as CPU, operating system, and others support it.

EIST will typically affect the computer only when it is using a very small amount of processing power or is in an idle state.

However, as and when the CPU is used for heavier workloads, it will not operate.

Yes, you can surely turn it off, but if you do so, you will lose the power saved by the processor when it is actually doing very little or nothing.

Therefore, the best thing to do is change the EIST to ‘Enabled,’ and for that, you will need to follow these steps below:

  • Start your computer
  • Enter BIOS or Basic Input Output System setting
  • Set Advanced BIOS Features
  • Click on CPU EIST Function
  • Click on Enable.

Apart from that, in order to make sure that Enhanced Intel SpeedStep Technology is performing at its optimal level and is not impacting the performance of the system adversely, you may also need to revise the Microsoft System Configuration Utility, or MSCONFIG.

The steps to follow for it are:

  • Go to the Start menu
  • Select run
  • Type “cmd” in the search box to open the Windows command prompt
  • Type “msconfig” on the command prompt
  • Hit Enter to open up the System Configuration utility
  • Click on the Boot tab on it
  • Click on the Advanced options and
  • Enable the Number of processors.
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Make sure that you choose the maximum number of processors from the drop-down list.

And, depending on the version of the Windows operating system, you may also need to make different changes in the Power Management setting as well.

For example, in Windows 7, you will need to set up the Power Management to ‘Balanced’ or ‘Saving’, but in Windows XP, you will need to set it to ‘Maximum Power Savings.’

Should You Disable EIST When Overclocking?

However, when it comes to overclocking, you may disable the EIST feature just as you may disable C-States or Turbo in your BIOS, and it is mainly due to its working process which may result in some issues while overclocking.

EIST basically works together with the C-states in order to find out the precise frequency required at a particular moment by increasing or decreasing the clock multiplier. It also changes the voltage to save power.

Both these changes may produce inconsistent results, which might lead to crashing of the system, especially when you overclock. Disabling EIST may boost the performance notably.

However, this performance benefit will be achieved at the expense of the power saving benefits, which will also be disabled at the same time when you disable EIST.

Therefore, ideally, it is your choice eventually. If you want a boost in the performance you may disable EIST, but if you want to save power, better leave it enabled.

Conclusion

EIST typically allows the CPU to save power when there is little or nothing to process, but at the same time, it also ensures that the processor performs at the highest level when it is needed.

Though available only in the core branded CPUs, this technology is surely worth keeping on for the computer to perform well.

About Taylor

AvatarTaylor S. Irwin is a freelance technology writer with in-depth knowledge about computers. She has an understanding of hardware and technology gained through over 10 years of experience.

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