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I have two systems I've just built. They both have i7 processors and Asus P8Z77 motherboards. When I run a simple processor loop benchmark that I wrote in Delphi some time back I get one machine showing nealry twice as fast as the other. I then used CPU-Z to dump me the details of the hardware and I see that the fast machine shows:

Processor 1                     ID = 0
        Number of cores         4 (max 8)
        Number of threads       8 (max 16)
        Name                    Intel Core i7 2700K
        Codename                Sandy Bridge
        Specification           Intel(R) Core(TM) i7-2700K CPU @ 3.50GHz
        Package (platform ID)   Socket 1155 LGA (0x1)
        CPUID                   6.A.7
        Extended CPUID          6.2A
        Core Stepping           D2
        Technology              32 nm
        TDP Limit               95 Watts
        Core Speed              3610.7 MHz
        Multiplier x FSB        36.0 x 100.3 MHz
        Stock frequency         3500 MHz

the slow machine shows:

Processor 1                     ID = 0
        Number of cores         4 (max 8)
        Number of threads       8 (max 16)
        Name                    Intel Core i7 2600K
        Codename                Sandy Bridge
        Specification           Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz
        Package (platform ID)   Socket 1155 LGA (0x1)
        CPUID                   6.A.7
        Extended CPUID          6.2A
        Core Stepping           D2
        Technology              32 nm
        TDP Limit               95 Watts
        Core Speed              1648.2 MHz
        Multiplier x FSB        16.0 x 103.0 MHz
        Stock frequency         3400 MHz

i.e the slow machine has a 2600k to the fast machine 2700k. The very different "Multiplier x FSB" must be significant but I dont understand how two processors with a very 'similar' number can be so different. To get the machines the same must I copy the processors or is there some clever setting that I can change?

Thanks for any help. Brian.

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closed as off topic by Michael Hampton, Shane Madden, EEAA, Bryan, SvW Nov 23 '12 at 23:02

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Your benchmark is probably too simple to show anything useful. –  David Schwartz Nov 23 '12 at 22:26

1 Answer 1

up vote 2 down vote accepted

Your processor Core Speed scales up and down based on usage (to save power, amongst other things). Multiplier x FSB = Core Speed so that'll change on the 2600k machine once it gets busy.

You can, if you really want, change your scaling governors to performance, if you want your Core Speed to always be the maximum it can ever be.

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Note that there's no reason you should do this and no reason you should want to do this. –  David Schwartz Nov 23 '12 at 22:40
1  
Great, thanks. I see now that the difference turned out to be cooling policy setting affecting clock multiplier. Thanks. –  Brian Frost Nov 25 '12 at 21:30

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