Windows XP Home not HyperThreading

I used to run a VIA KT400 with an Athlon XP 2200.
Recently, I upgraded to a i865P with a Northwood-3.2/HT (on an Asus P4P800 Deluxe).
First, Windows wouldn't boot, because apparently it was unhappy about the unexpected switch of hardware. However, I totally re-installed and re-registered, and it's all better now.

I have enabled HyperThreading in the BIOS. The BIOS boot screen shows the HT Pentium 4 logo. I have verified with a bit of code that the chip has two logical CPUs available, according to Intel sample code for HyperThreading detection. The Device Manager shows two processor devices.

However, when I query the kernel for processor affinity masks, there's only a single processor to bind affinity to. Also, when I query current ACPI CPU number using CPUID, I never get anything back other than first CPU. Last, the CPU Load indicator only shows a single CPU load value.

Thus, I believe that the scheduler/kernel believes there's a single CPU, even though the rest of the system thinks there's two. Why is this, and what can I do about it?
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More about windows home hyperthreading
  1. I dont think xp home supports hyperthreading. You need to get xp pro. search in the forums theres other comments on this.
  2. Home does support HT, just not SMP. (Two physical processors).

    Was HT enabled when you first installed XP or did you enable it after installing? That might have made the difference.

    <font color=red> If you design software that is fool-proof, only a fool will want to use it. </font color=red>
  3. you need to download a driver for it. its available from intel

    :cool: :eek: :redface: :frown: :lol: :mad: :eek: :smile: :tongue: :wink: :evil:
  4. Thanks for the replies.

    In fact, Microsoft claims that XP Home supports HyperThreading (on a single die).

    Intel claims that there is nothing to download; Microsoft ships the necessary files. Checking their download page for Pentium 4 processors, there's only the frequency ID utility.

    Hyper threading may have been off when I installed, I don't recall. Re-installing again is no kind of fun, but I can't think of anything else to try. Thanks for the tip!

    (I've already un-installed and re-installed various system components, such as CPU driver, Microsoft ACPI support, and HAL)
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