Intel SpeedStep Technology

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The Intel SpeedStep Technology (SpeedStep for short or EIST for " Enhanced Intel SpeedStep Technology ") is an energy-saving function in notebook and desktop processors from Intel .

General

Speedstep was developed to extend the battery life of notebooks (more generally: to reduce the power consumption of the main processor). SpeedStep is a name for a dynamic voltage / clock management. Speedstep 1.1 detects whether the notebook is plugged into the socket or just on the battery. In mains operation, the processor clocks at full rated power and the maximum computing power is available. If the notebook is in battery mode, the clock frequency is reduced, which lowers power consumption. With a reduced frequency, the voltage can also be reduced. Since the energy expenditure depends on the square of the core voltage of the chip, the voltage reduction has the greatest effect on consumption. The lower energy consumption extends the battery life .

As of Speedstep 2.1, the CPU has so-called "Dynamic Switching", here the CPU load is recognized and the clock rate is adjusted accordingly. If the CPU is idling, it automatically clocks with the lowest clock. However, if the CPU is challenged, for example by a computationally intensive application, the CPU switches the clock speed up within milliseconds and offers full performance. With special programs such as B. Speedswitch-XP, Notebook-Hardware-Control or RMClock, precise regulations can be set how Speedstep should behave, e.g. B. Dynamic switching in network operation and "fixed minimum processor clock" in battery operation.

Basically, with a notebook that is capable of dynamic switching, it hardly makes sense to fix the clock rate in mains operation at full load, since the unnecessarily high computing power also affects the waste heat generated and therefore the fan operated unnecessarily faster and louder must become. But not only the processor is a major consumer; other components such as the screen backlight , hard drives , controllers and dedicated graphics cards must be optimized for low energy consumption.

In notebook processors

In notebooks, SpeedStep also influences other components and regulates e.g. B. the screen brightness. The software also knows intermediate steps in the clock rates and several profiles in order to either extend the runtime or provide more computing power. With the introduction of the Pentium M , the partially deactivatable cache was introduced, which further reduces energy consumption.

SpeedStep is used in different versions in:

The Mobile Celeron and its successor, the Celeron M, do not have a SpeedStep.

In desktop and server processors

Due to higher clock frequencies and greater chip complexity and the associated heating and cooling problems, Intel also introduced energy-saving measures in many standard processors.

First of all, an extended halt command, the "Enhanced Halt State" (C1E), was integrated into Pentium 4 / Xeon processors (from E0 stepping): While an operating system is in a phase in which no work is pending (idle state) , can only switch off the processing units of the CPU via the normal stop command, it can additionally reduce the clock rate and the voltage via C1E during operation. However, the energy savings were rather moderate in the beginning, since the reduction in clock and core voltage is relatively low and there are only two levels: idle or full load. Modern desktop CPUs, like notebook CPUs, lower the clock rate over several stages.

Since the Pentium 4-600 series (N0 stepping), SpeedStep has been found in almost all Intel desktop processors in the middle and upper market segment.

Versions

There are different versions of Intel SpeedStep Technology that are used in different processors:

version processor
1.1 Intel Pentium III Coppermine
2.1 Intel Pentium III Tualatin
2.2 Intel Pentium 4 M & Mobile Pentium 4
EIST Intel Pentium D (except 805 and 820), Stepping B-1 of the 631, 641, 651, 661, 930, 940, 950 versions only faulty
EIST Intel Pentium 4 6xx, 5x1 and 5x0J
EIST (extended) Intel Pentium M
EIST Intel Core 2 Duo, Intel Core 2 Quad, Intel Core 2 Xtreme, Intel Core i3, Intel Core i5, Intel Core i7
EIST Intel Celeron E1x00
EIST Intel Atom N270
Demand Based Switching Intel Xeon (various models), Core i7 (D0 stepping)

Problems

Due to the low energy consumption of the processor in the meantime, there are high-frequency, audible vibrations on some poorly designed motherboards. These have their origin in the copper coils of the voltage converters, which convert the voltage of the power supply unit into the voltage of the processor.

According to a Heise-online article, "Machine Check Exceptions" (MCE) occur with some users on Broadwell processors, especially with Linux -based operating systems. Ubuntu 14 seemed to be most frequently affected, Fedora 22 less often. Systematic crashes (blue screens) were also reported under Windows, for example when installing Office 2016 or with some Steam games. The problems mostly disappeared when you switched off SpeedStep .

See also

Web links

Individual evidence

  1. ↑ Andreas Stiller: Furthermore SpeedStep problems with Broadwell processors. Heise, October 9, 2015, accessed October 10, 2015 .
  2. ↑ Michael Larabel: Working Around The Intel Core i7 5775C Broadwell Stability Issue On Linux. Phoronix, July 5, 2015, accessed October 10, 2015 .