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Solved: Windows XP insists on ignoring my Dual-Core Processor

Discussion in 'Windows XP' started by jameshoward, Oct 18, 2008.

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  1. jameshoward

    jameshoward Thread Starter

    Oct 18, 2008

    short explanation for those who don't have the time to read it all:

    My Windows XP Home SP2 refuses to recognize Pentium D Dual-Core 2 x 3,4 Ghz processor, even though hotfix KB896256 has been installed properly. Device manager shows two processors but task manager only shows workload for one core. Cubase SX (sequencer software i use) does not allow me the use of 2 cores, so i assume it can not properly recognize them through the operating system.

    Any help would be appreciated!

    Detailed problem description

    i am expiriencing an issue with Windows XP SP2. When i initially installed Windows XP a year ago, everything worked fine. After installing Windows Update KB896256 my Dual-Core processor was being recognized and used. In the task manager i was able to see the workload of both processor cores seperately.

    A few months ago i had a problem with the system and had to repair the Windows XP installation. I could have reinstalled it, but i am using the machine for music production and it literally takes half a day to install all the software again.

    The repair went fine and Windows XP loaded perfectly upon the first startup. However, i soon noticed that the machine was having much less processing power than before. Finally i realized that it was not recognizing my Dual-Core Processor anymore. I then re-installed KB896256 but it did not help. I checked the BIOS settings but everything was fine (i never changed them in between anyway).

    In fact the Windows device manager now shows two processors but the task manager shows only one core. And Cubase SX - the music sequencer software i am using - declines to offer me the usage of multiple cores - mainly, i assume, because it does not recognize that i have a Dual-Core system.

    This has become pretty disturbing and is keeping me from doing my work! I therefore would need your advice. Anything helpful would be appreciated!
    Thank you very much!

    - James Howard

    Ps.: My machine specs: Windows XP Home SP2 Build 2600 on Pentium D Dual-Core 2 x 3,4 Ghz, ASUS board, 2 GB RAM
    Other installed Hotfixes: KB885222 and KB904412 ensuring proper usage of FireWire devices.
  2. peacox


    Oct 11, 2008
    Have you checked Task Manager/view/CPU History/One Graph per CPU ?
  3. jameshoward

    jameshoward Thread Starter

    Oct 18, 2008
    Yes, i have tried that.

    Thank you. I have finally found the solution to the problem - and the actual cause.

    The system was running on a Uniprocessor ACPI - which was caused by not choosing the correct HAL-driver during repair/install.

    This can be fixed in two ways: reinstall / repair with correct driver or trick the system, by replacing the three kernel-crucial files in the windows\system32 folder with the correct ones for ACPI-Multiprocessor-PC.

    There are three files involved in this in your windows/system32 directory:


    The versions you need may be found in windows/servicepackfiles/i386, in the KB896256 hotfix package or on the Windows XP SP2 CD:


    Replacement can only be done in SAFE MODE. One must delete (or rename) hal.dll, ntoskrnl.exe and ntkrnlpa.exe, then place the new three files in windows\system32 and give them the names of the originals.

    Upon the next reboot Windows XP will use those new files instead of the old ones and therefore consider the system to be a ACPI-Multiprocessor-PC.

    One can check the results in the device manager, under "Computer" it should say "ACPI-Multiprocessor-PC".

    Also, the task manager will, if configured accordingly, show both processor core's workload seperately.

    Good luck!
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