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AndrewR, Computer Support Specialist
Category: Computer
Satisfied Customers: 208
Experience:  Ten years of experience working in IT.
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Where can I disable hyperthreading or reduce the number of

Customer Question

Where can I disable hyperthreading or reduce the number of logical cores?

No option in the BIOS. Anywhere in the windows registry?
I have an core i7 processor (720qm) running windows 7 home premium. Insyde Bios 5.31.

BIOS is H2O should support UEFI. How can I access and UEFI shell or install it..? Would a windows or BIOS upgrade help? I have already the latest BIOS but maybe I can switch manufacturers..

I spent days researching... any help is very appreciated!
Submitted: 7 years ago.
Category: Computer
Expert:  R.J. Poirier replied 7 years ago.

Thank you for posting your question.

Why are you trying to step down your machine ? Is it to run a particular program? What is the make and model of your machine?
Customer: replied 7 years ago.

I have bought this machine to speed up my share trading/simulation software "Metastock 10".

Unfortunately, it turns out that Metastock does not use the different cores as it creates only one thread. Now this is a Metastock problem and nothing I can do about. However, because of hyperthreading the notebook creates 4 additional logical cores to the existing 4 physical ones which effectively reduces the CPU usage to 12.5% not 25% as it would be with 4 cores.


By switching of Hyperthreading i.e. removing the logical cores I have hopes that Metastock will be able to use one full core and performance would double compared to now.


Notebook: HP Pavilion 2090eo with core i7 720qm processor.

Possibilities to fix this:
1) UEFI has an option to switch of hyperthreading. My BIOS should support "Insyde h2o" UEFI but I don t know how to access the UEFI shell etc..
2) HAL up/down grade in Windows? Change from Multiprocessor to uniprocessor was possible in XP. My device manager shows ACPIx 64 based PC under Computer.
3) Migration to another BIOS that supports that Hyperthread switch (e.g. Phoenix) possible?
4) Reinstallation of windows7 in a different way that enables UEFI or more options in BIOS ?
5) Down or upgrade of Windows?
6) Any settings in Windows or the registry that could disable those logical cores? I have tried disabling the last 4 cores in msconfig but did not improve performance - probably because 2 of the 4 cores were still not physical.

I found that many gamers seem to be able to disable HT in the BIOS.. why can t I with the latest notebook?

The BIOS options are unusually basic I think. I have also tried to enable and disable virtual Technologies.. still all 8 cores there..

Expert:  R.J. Poirier replied 7 years ago.
What is the make and model of your machine?
Customer: replied 7 years ago.

Make: Hewlett Packard

Model: Pavilion 2090eo


with core i7 720qm processor. Here is a link to HP s driver download site for this model:

Expert:  R.J. Poirier replied 7 years ago.
you could disable the multi-processor HAL in the device manager and change the driver for ACPI to single processor PC and back to multi processor PC when required.
Customer: replied 7 years ago.

Disabling and uninstalling is greyed out.


updating might work but I would need to get a uniprocessor driver for the hal for windows 7 from somewhere..

Appearently in XP this could only be done by reinstalling the operating system.


It s nearly 4 am here and I will go to bed... thanks so far.. I wish it would be as simply as updating the hal.. maybe it is..

Expert:  R.J. Poirier replied 7 years ago.
Ok I will post an update later on as it is only 9:45 pm here.
Expert:  R.J. Poirier replied 7 years ago.
Ok lets give this a try... when logged into windows click on the start menu and in the search box type msconfig. Now when you bring up the MSConfig click on the boot tab now click on advanced options. Once the new window opens click on the check box next to the number of processors and set this to 1. Now say ok to everything and restart your machine. You should now be running with a single core.
Customer: replied 7 years ago.

That downgrades my 4 physical cores to one and would concentrate all background applications on this one core - not just Metastock. So overall it does not achieve what I am looking for: faster performance of my trading application. I am happy to keep those 4 cores - they are doing a good job but the logical ones are deteriorating speed for this application.

I know I can switch hyperthreading off in the UEFI shell. I would like to focus on this solution as this should be the cleanest..(unless there is some safe alternative)

How do I know if my computer is UEFI compatible?
How would I access the UEFI shell if I have it?
How can I install UEFI if I don t have it?

I cannot see any partition other than the main/system C: and a recovery partition NTFS from which I installed Windows7 on first startup.

Can you help here?

Expert:  David L replied 7 years ago.

So just to clarify, you now need assistance finding a way to access the efi shell correct?
Customer: replied 7 years ago.
Expert:  David L replied 7 years ago.
If you reboot and then immediately press F2 on boot up, you should be able to access the shell as long as it is installed.
Customer: replied 7 years ago.

I did this many times. Unfortunately no shell option in the boot manager. You are right the shell should be in the efi bootmanager.

I can access that EFI diagnostics program from the current bootmanager but no shell or boot from file option. On the HP_TOOLS partition which - I understand is the EFI partition - I can also only find evidence of the diagnostic program.


I suspect I might need to install the shell and/or the efi bootmanager from somewhere.

Perhaps during the installation of windows I might get an option to install from EFI bootmanager? I wonder if it makes any difference for the installation that I have assigned a drive letter to the HP_TOOLS partition. This seems a tough problem..

Expert:  AndrewR replied 7 years ago.
Let's attack this from a different direction.

You want this application to only utilize ONE of your CPU cores.

The easiest way to do this is to start your task manager (hit ctrl-alt-delete) click the processes tab, right click the process you're trying to run on a single core, and go to "set affinity."

There's a way to do this by using a utility to modify each individual .exe, but it was still quite difficult. Fortunately, there are now applications available that will create profiles for each application, that will better manage affinities and assign specific applications to specific cores PERSISTENTLY.

Try this.

Edited by AndrewR on 2/5/2010 at 2:00 AM EST
Customer: replied 7 years ago.

Hi Andrew,


Sorry for the delay - I was very busy.

While I find it useful, the utility does not solve the problem I trying to tackle. The programm I need to run fast only creates one thread. If I assign one out of 8 logical cores to it - it still only uses half a physical core. You can assign priorities and affinities also in the Windows 7 task manager.


Even if we configure windows to boot with 4 cores instead of 8 - it only uses 4 out of 8 logical cores, not 1 out of 4 physical cores - I still only get half a core performance. this is reflected in the overall processor usage number of 13% and the calculation speed for a certain task of my trading software.


I also now think that finding a registry tweak can not solve this as windows gets the info from the bios or EFI that there are 8 cores. Switching off any of those would not help. It needs to know that there are only 4. So accessing EFI or changing/modifiying the BIOS seem the only option.


Unless there is such a utility that can create multiple threads out of one thread - but this would probably be in the news...


..or the there is something to tweak the motherboard to make it hyperthreading unfriendly..BIOS/EFI/motherboard determine the ability to hyperthread (HT). Can we make any of these HT incompatible..? Can t believe they sell such a basic BIOS.

Expert:  AndrewR replied 7 years ago.
I'll do some more research and report back. Meanwhile I'm going to allow other experts to get their $.02 in.