Intel Turbo Boost
Encyclopedia
Intel Turbo Boost is a technology implemented by Intel in certain versions of their Nehalem- and Sandy Bridge
-based CPUs, including Core i5 and Core i7 that enables the processor to run above its base operating frequency via dynamic control of the CPU's "clock rate
". It is activated when the operating system
requests the highest performance state of the processor. Processor performance states are defined by the Advanced Configuration and Power Interface (ACPI)
specification, an open standard
supported by all major operating systems; no additional software or drivers are required to support the technology. The design concept behind Turbo Boost is commonly referred to as "dynamic overclocking
".
The increased clock rate is limited by the processor's power
, current and thermal
limits, as well as the number of active cores and the maximum frequency of the active cores. When workload on the processor calls for faster performance, and the processor is below its limits, the processor's clock will increase the operating frequency in regular increments as required to meet demand. Frequency increases occur in increments of 133 MHz for Nehalem microarchitecture processors and 100 MHz for Sandy Bridge microarchitecture
processors. When any of the electrical or thermal limits are reached, the operating frequency automatically decreases in decrements of 133 MHz/100 MHz until the processor is again operating within its design limits.
discusses "Turbo Boost" technology as a new feature incorporated into Nehalem-based processors released in the same month.
A similar feature called Intel Dynamic Acceleration
(IDA) was available on many Core 2 based Centrino platforms. This feature did not receive the marketing treatment given to Turbo Boost. Intel Dynamic Acceleration dynamically changed the core frequency as a function of the number of active cores. When the operating system instructed one of the active cores to enter C3 sleep state using the Advanced Configuration and Power Interface
(ACPI), the other active core(s) dynamically accelerated to a higher frequency.
For Core i7-920XM.
The normal operating frequency is 2.0 GHz. Turbo is indicated as: 2/2/8/9 in which the first number is the multiple of 133.33 MHz supported when four cores are active, the second number is the multiple for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.0 GHz) in steps of 133 MHz to:
For Core i7-2920XM.
The normal operating frequency is 2.5 GHz. Turbo is indicated as: 7/8/9/10 in which the first number is the multiple of 100 MHz supported when four cores are active, the second number is the multiple for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.5 GHz)in steps of 100 MHz to:
Sandy Bridge (microarchitecture)
Sandy Bridge is the codename for a microarchitecture developed by Intel beginning in 2005 for central processing units in computers to replace the Nehalem microarchitecture...
-based CPUs, including Core i5 and Core i7 that enables the processor to run above its base operating frequency via dynamic control of the CPU's "clock rate
Clock rate
The clock rate typically refers to the frequency that a CPU is running at.For example, a crystal oscillator frequency reference typically is synonymous with a fixed sinusoidal waveform, a clock rate is that frequency reference translated by electronic circuitry into a corresponding square wave...
". It is activated when the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
requests the highest performance state of the processor. Processor performance states are defined by the Advanced Configuration and Power Interface (ACPI)
Advanced Configuration and Power Interface
In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system....
specification, an open standard
Open standard
An open standard is a standard that is publicly available and has various rights to use associated with it, and may also have various properties of how it was designed . There is no single definition and interpretations vary with usage....
supported by all major operating systems; no additional software or drivers are required to support the technology. The design concept behind Turbo Boost is commonly referred to as "dynamic overclocking
Overclocking
Overclocking is the process of operating a computer component at a higher clock rate than it was designed for or was specified by the manufacturer, but some manufacturers purposely underclock their components to improve battery life. Many people just overclock or 'rightclock' their hardware to...
".
The increased clock rate is limited by the processor's power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
, current and thermal
CPU power dissipation
Central processing unit power dissipation or CPU power dissipation is the process in which central processing units consume electrical energy, and dissipate this energy both by the action of the switching devices contained in the CPU and by the energy lost in the form of heat due to the impedance...
limits, as well as the number of active cores and the maximum frequency of the active cores. When workload on the processor calls for faster performance, and the processor is below its limits, the processor's clock will increase the operating frequency in regular increments as required to meet demand. Frequency increases occur in increments of 133 MHz for Nehalem microarchitecture processors and 100 MHz for Sandy Bridge microarchitecture
Sandy Bridge (microarchitecture)
Sandy Bridge is the codename for a microarchitecture developed by Intel beginning in 2005 for central processing units in computers to replace the Nehalem microarchitecture...
processors. When any of the electrical or thermal limits are reached, the operating frequency automatically decreases in decrements of 133 MHz/100 MHz until the processor is again operating within its design limits.
History
An Intel white paper of November 2008discusses "Turbo Boost" technology as a new feature incorporated into Nehalem-based processors released in the same month.
A similar feature called Intel Dynamic Acceleration
Intel Dynamic Acceleration
Intel Dynamic Acceleration sometimes called Dynamic Acceleration Technology is a technology created by Intel Corp. to boost the speed of an applications running on one of the cores of a multi-core Intel processor...
(IDA) was available on many Core 2 based Centrino platforms. This feature did not receive the marketing treatment given to Turbo Boost. Intel Dynamic Acceleration dynamically changed the core frequency as a function of the number of active cores. When the operating system instructed one of the active cores to enter C3 sleep state using the Advanced Configuration and Power Interface
Advanced Configuration and Power Interface
In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system....
(ACPI), the other active core(s) dynamically accelerated to a higher frequency.
Example
(Taken from the list of Intel Core i7 microprocessors.)For Core i7-920XM.
The normal operating frequency is 2.0 GHz. Turbo is indicated as: 2/2/8/9 in which the first number is the multiple of 133.33 MHz supported when four cores are active, the second number is the multiple for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.0 GHz) in steps of 133 MHz to:
| # of cores active | # of Turbo Steps | Max frequency | Calculation |
|---|---|---|---|
| 3 or 4 | 2 | 2.26 GHz | 2000 + (2 × 133) = 2000 + 266 ≃ 2266 |
| 2 | 8 | 3.06 GHz | 2000 + (8 × 133) = 2000 + 1066 ≃ 3067 |
| 1 | 9 | 3.20 GHz | 2000 + (9 × 133) = 2000 + 1199 ≃ 3200 |
For Core i7-2920XM.
The normal operating frequency is 2.5 GHz. Turbo is indicated as: 7/8/9/10 in which the first number is the multiple of 100 MHz supported when four cores are active, the second number is the multiple for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.5 GHz)in steps of 100 MHz to:
| # of cores active | # of Turbo Steps | Max frequency | Calculation |
|---|---|---|---|
| 3 or 4 | 7 | 3.20 GHz | 2500 + (7 × 100) = 2500 + 700 ≃ 3200 |
| 2 | 9 | 3.40 GHz | 2500 + (9 × 100) = 2500 + 900 ≃ 3400 |
| 1 | 10 | 3.50 GHz | 2500 + (10 × 100) = 2500 + 1000 ≃ 3500 |
See also
- Nehalem microarchitecture
- Sandy Bridge microarchitectureSandy Bridge (microarchitecture)Sandy Bridge is the codename for a microarchitecture developed by Intel beginning in 2005 for central processing units in computers to replace the Nehalem microarchitecture...
- Hyper-threadingHyper-threadingHyper-threading is Intel's term for its simultaneous multithreading implementation in its Atom, Intel Core i3/i5/i7, Itanium, Pentium 4 and Xeon CPUs....