Pentium 4 Has Lost Its Hyperthreading


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In Vista I noticed that my computer was not coping with the same heavy loads as usual and looked in the task manager. Only 1 CPU showing when there always used to be 2. I know that Pentium 4 is only 1 CPU but it shows as 2 in TM when 1 graph per CPU is selected.

I did set NUMBER_OF_PROCESSORS in CMD Prompt and it told me that I only had 1 (should be 2 if HT enabled).

It's acting as it should in XP and Windows 7 - only Vista is effected and in the attached picture that Processor name spelled out used to read merely ACPI Multi-Processor (or words to that effect).

I've tried disabling HT in the BIOS rebooting and then re-enabling it again but it had no effect.

What to do?


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Tried that but on second thought it wouldn't help as this is really a hardware issue with Vista recognizing it. When I've finished burning the DVD I'm doing right now I'll uninstall the processor in device manager and reboot. Hopefully the system will re-enable the HT.


OK cured it.

I found this method online posted by someone who had a quad-core showing as only 2 so adapted it to suit.
In the Device Manager shown above I uninstalled both the Processors and rebooted.
They duly reinstalled and I had to reboot again.
Then I went to Start/Run and entered msconfig, OK'd UAC and once it opened went to the Boot tab/Advanced Options
There I unchecked the number of processors (which showed as only 1)
I then checked "Detect HAL" and rebooted. worked.
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Yes indeed, very weird. I think I have a ghost. My TV turned itself on the other day, would that count as weird?
You can also control the proccessors for entries using EasyBCD too...
Can't help you with your ghost problems though :smile:
LOL, thanks Justin. I have EasyBCD installed in XP which is my other hard drive, would that make a difference? The only OS this happened to was Vista for some unknown reason.
Nope. In advanced options you can set the number of proccessors for an entry, specifying 0 to reset it.