Sandybridge, Speedstep/turbo and you

Discussion in 'hardware' started by Sully, Sep 18, 2011.

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  1. Sully

    Sully Registered Member

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    Not much to report here, just a very strange thing I found.

    If you did not know it, you can choose to boot your system with more than one core of your cpu. The default is one core. In the case of a sandybridge with hyperthreading, you have up to 8 cores.

    By using MSCONFIG you can can set how many cores to boot with. With my core2duo system, I set it to 2 cores and it did make a noticeable difference. I enabled it to 4 on my new 2600k system, and once I did, speedstep and thus turbo stopped. The cpu ran at its default 3.4 ghz rate, and did not go up nor down.

    I was not aware that option would do such a thing, as I though the BIOS handled the speedstepping independently of OS. Evidentily not.

    Wierd.

    Sul.
     
  2. Hungry Man

    Hungry Man Registered Member

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    By default your OS boots up with one core while it initiates some things with CMOS and then after that all cores are used.
     
  3. Keyboard_Commando

    Keyboard_Commando Registered Member

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    I can confirm messing with msconfig's control over the amount of processors used at boot will show up strange happenings. When I first got my I7 2630QM laptop I followed a Win7 tweak guide - I had 8 cores to choose from in MSCONFIG - oh yipeee 8 cores to choose from this will fly at boot (I thought). The default MSCONFIG setting was showing just 1 core - So I enabled 2 cores to see if it would be stable, the guide recommended 2 or 4 (looking back I can see how outdated this tweaking guide is). When I checked CPU-Z it only showed up the 2 cores, same with taskmanager, and turbo had gone AWOL.

    Changing the MSCONFIG boot processor setting to 0 will reset the default cores - Which is what I did. Get Windows 7 to detect your new multi-core processor

    tweaking-myth-increase-boot-performance-for-multi-core-users-with-msconfig/

    Gotta be careful with outdated tweaking guides.
     
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