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How Does Intel Turbo Boost Work?

Preeti Sunil
In November 2008, Intel published a white paper describing a new feature, incorporated in its latest release of Nehalem-based processors, called Intel Turbo Boost Technology. This high performance technology essentially allows processors to run faster than the base frequency by dynamically controlling its clock rate under certain constraints.
This story attempts to demystify this popular design concept of 'dynamic overclocking'.
When a processor is tweaked without add-on hardware to run faster than its base configuration, the result is that instead of processing x number of instructions per second (for which the original design was built), it is now capable of handling x+n instructions per second. In simple terms, it's going to process much more and therefore, faster than what it was built for.
Intel's trademarked Turbo Boost Technology enables higher performance by making available an increased processor core frequency, provided some dependency conditions are met.
Unlike manual overclocking by manipulating clock speeds on the BIOS, dynamic overclocking is automatic and is based upon constantly evaluating if the dependencies are met, commonly referred to as dynamically assessing headroom. Let us explore these dependencies in detail and find out how the Intel Turbo Boost Technology works.

Working of Intel Turbo Boost Technology and Processor Dependencies

Unlike overclocking which causes overheating of hardware making it prone to damage, Intel Turbo Boost is a technology built into the design of the processor versions that support it.
The biggest benefit of this design is faster performance without exceeding the electrical and thermal specifications of the core, thus conserving energy when it is not needed.
However, the increased core frequency is constrained by the following factors.
  • Estimated processor power and current consumption
  • Estimated processor temperature
  • Number of active processor cores (they dictate the maximum frequency)
If the current application workload isn't keeping all cores fully busy and pushing right up against the chip's Thermal Design Power (TDP is the maximum amount of power the chip can withstand with help from the cooling systems) limit, Turbo Boost can increase the clock speed of each core individually to derive more performance out of the chip.
Under the above constraints of TDP, the processor can increase its clock speed in steps of 133.33 MHz. All active cores in the processor will maintain the same frequency.
Whatever power the other two or three cores would have consumed can be redirected over to the active cores, allowing them to run at higher speeds. The highest performance state when requested by the Operating System, activates the Intel Turbo Boost Technology.
The operating configuration, platform design and workload parameters dictate how long the Intel Turbo Boost state will be maintained. Under ideal conditions, the technology positively influences the performance of both multithreaded and single-threaded workloads.

Advantages of Dynamic Overclocking

Intel Turbo Boost Technology being a dynamic feature that kicks in when certain conditions are met, the user cannot predict when the system will switch to the "turbo mode".
However, it still provides a solution such that there's no compromise involved while choosing a dual core or quad core processor. Dual core processors have greater clock speeds because, the more number of cores in quad core meant increased power consumption and caused overheating.
One had to make a choice also between applications that favored dual core or quad core. However, with Intel Turbo Boost, any idle core would go into a lower power state and the active cores would be dynamically overclocked thus eliminating compromise!
A new version of Core i7 processor has a feature that enables operation at base clock speed when the system is battery-powered but switches to Turbo Boost, doubling its clock speed, when plugged in.

How to Use Turbo Boost Technology

The important thing to know is that Intel Turbo Boost technology will work only on the following supported processor families.
  • i7 mobile and desktop processors
  • i7 processor extreme edition
  • i7 mobile processor extreme edition
  • i5 mobile and desktop processors
In the previous processors, the Intel Turbo Boost Technology is enabled by default. A BIOS switch can be used to disable it, however, this is not recommended.
There are no further settings available for the user to intervene in the operation, activation or frequency specification of the Intel Turbo Boost Technology. An optimized version of the original Intel Turbo Boost Technology, Intel Turbo Boost Technology 2.0 is incorporated in 2nd Generation Intel core processors, providing even more performance.
To view the Turbo Boost in action, you may download a tool known as the Intel Turbo Boost Technology Monitor. The Intel Processor Identification Utility will enable you to view the highest Turbo Boost frequency on the supported processor.
If you're only using your PC for Internet browsing, working on a few word processing and spreadsheet applications and mostly just checking your email, you might not find much use for the Intel Turbo Boost Technology although you may prefer it to manual overclocking.
However, if you're mostly working with HD media or video-intensive applications, 3D gaming or multitasking compute-intensive applications, then this on-demand performance technology that intelligently allocates extra processing power to match workload, is as futuristic as it gets.
Traditionally the playing field of gaming enthusiasts and power users, overclocking has found its way into modern-day processors for good. Preset processor clock speeds seem to have become a thing of the past. Adaptive performance of processors to suit the demands of the user in a dynamic and flexible way seems to be the future.