1 Reply Latest reply on May 4, 2010 9:29 AM by RJL190365

    Different clock speeds at the same processor

    cbanogueira

      Hello. I'm running a research about process scheduling in processors with different clock speeds. Actually, my question is: can processors like Core i7, Core i5 or Core 2 Duo work having different clock speeds at each of it's cores? For example: a Core i7 having 6 cores where each one can work at the limit of 3.33GHz. Due to power consumption or thermal restrictions or even due to the Turbo Boost technology, could these cores work at: core 1, 3 and 4 = 1.7GHz, cores 2 and 5 = 2.0GHz and core 6 = 3.3 GHz?  Forgive me if I mispelled any word. My english is not that good. Thank you!

        • 1. Re: Different clock speeds at the same processor
          RJL190365

          The processor does not quite work like that. 3.33GHz is the nominal speed of that i7-980X that you've mentioned. Lower clock speeds than 3.33GHz are due to Intel's Enhanced SpeedStep, which is enabled by default on all i7/i5/i3 motherboards. In the i7 processors, the SpeedStep feature sets the processor multiplier (in relation to the processor's base clock speed of 133MHz) all the way down to 12x at idle (this results in an "idle" clock speed of 1.60GHz). But as soon as you run an application which puts some load on the processor, all six cores get bumped up to 3.33GHz. The Turbo Boost feature gets activated if you are running applications which demand the full processing power. In this mode, all six cores get bumped up another 133MHz to 3.46GHz. From there, if you are running CPU-intensive applications which use only one or two threads, one or two of the cores get bumped up by another 133MHz step, to 3.60GHz (while the other four cores remain at 3.46GHz).

           

          The above is specific to the i7-980X processor. On other i7-9xx series processors which have four physical cores, only one of the cores get bumped up by two 133MHz steps over the nominal speed (for example, the i7-930, whose nominal clock speed is 2.80GHz, only uses the two-level Turbo Boost on apps which make use of only one core - in which case the Turbo Boost sets the clock speed on the one core from an already boosted 2.93GHz to 3.06GHz).

           

          The above all refer to LGA1366 processors. LGA1156 processors, on the other hand, have multiple levels of Turbo Boost which vary by processor.

           

          Hope this helps.