Processors - Limit Number Used by Windows 7

How to Set the Number of Processors or Cores to be Used by Windows 7​

   Information

If you have a multiple core processor (CPU) or multiple processors, then this will show you how to limit the number of processors to be used by Windows 7, or to make sure that you are using all processors.

This can be handy for troubleshooting and debugging purposes to be able to determine if there is a problem with a single processor/core, or for a programmer to test their code against a single core while still running on their multi-processor/core system.

Windows 7 uses all of your processors or processor cores by default.

   Note

You must be logged in as an administrator to be able to do this.

Here's How: 1. Open the Start Menu, then type msconfig and press enter.

2. If prompted by UAC, then click on Yes.

3. Under the Boot tab in System Configuration, click on the Advanced options button. (see screenshot below)
4. To Have Windows 7 Use All Processors or Cores A) Uncheck the Number of processors box, and click on OK. (see screenshot below)
NOTE: This is the default setting.
B) Go to step 6.
5. For Windows 7 to Use a Specified Number of Processors or Cores A) Check the Number of processors box, then select how may processors or cores you want Windows 7 to only be able to use in the drop down arrow menu and click on OK.
6. Check the Make all boot settings permanent box, and click on OK. (see screenshot below)
NOTE: You will still be able to come back and make changes again if you like.
7. Click on Yes. (see screenshot below)
NOTE: You will still be able to come back and make changes again if you like.
8. Click on the Restart button. (see screenshot below)
WARNING: This will restart the computer immediately. Make sure you save and close anything open that you do not want to lose first.

   Tip

If you checked the Don't show this message again box and would like to restore this Restart box to display again, then see: How to Restore the System Configuration Restart Prompt in Vista or Windows 7

9. When Windows 7 is finished restarting, it will now be using only the number of processors or cores that you specified.
NOTE: You can look in Task Manager (CTRL+SHIFT+ESC) to confirm this number of processors or cores. You will have one graph per core in the CPU Usage History area.
That's it,
Shawn

Related Tutorials

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• How to Set Maximum Memory to be Used by Windows 7 and Windows 8
• How to Change the Displayed Name of the Processor in Windows 7, XP, and Vista

 

[Brink]

Hello Max,

There is no need for this to be removed since it can be very helpful to those that need it. Even for inexperienced users, this tutorial is layed out easily enough for them to be able to set it back to default.

The default is to have the box unchecked instead to use all processors/cores. It does not matter what the number is in the drop down list when the box is unchecked since that number only matters when the box is checked to limit the amount of processors/cores to that number.

I agree that this setting should be left alone to it's default of being unchecked unless you have a need to limit them for testing purposes.

 

[MadMaxData]

Okie dokie, your the head honcho. However, I'm thinking that maybe it should be clear in the first post that this setting only affects users who are running two different physical processors, and it has no affect on single CPU's with a dual or quad cores. It seems like people are getting confused as to it's actual purpose, and function.

 

[Brink]

No problem. It can reduce the amount of both multi-core processors as well as multi physical processors used by Windows 7 though. I tested this myself on my single quad core CPU, and it reduced the CPU Usage History graph in Task Manager to how many I limited it to.

 

[MadMaxData]

Hmmm, that's odd. I've had both my cores in the CPU history graph since installation.

 

[Brink]

By default you would have all cores available.

In the boxed in red area in the screenshot of my Task Manager with my single CPU with 4 cores below is what is reduced by the number I set if I check the box in this tutorial and set the number of processors/cores to use instead.

 

[MadMaxData]

Yeah I got what you were saying. However, I still cringe at the prospect of n00bs messing around in advanced system settings. Call it a quirk.

 

[Brink]

Oh, ok.

Well, they have to learn some how, and we can help to hear.

 

[manjunath]

brink,it I check make all boot settings permanent,will I be able to change settings boot settings later??

 

[Brink]

Hello Manjunath,

Yes, you can still make changes to this at anytime that you would like afterwards, and check the box again afterwards. It's just to make it the new default startup process.

Unless you are doing testing by limiting your processors, you should leave the Number of processors box unchecked so that Windows 7 uses all available processors/cores by default.

Hope this helps,
Shawn

 

[stephena]

Hey i have an issue with my number of processors. Im kind of a noob at this, but I had a friend change my processor number from one to four. I thought this was making my computer work much harder and making it overheat, but thats because i was on a bed. I found that out after i changed it back to one, and now i cannot change it back to four processors. It only displays one of them. If anybody has a solution to this, i would appreciate it sooo much. Please help. My computer is very slow now.

 

[Brink]

Hey i have an issue with my number of processors. Im kind of a noob at this, but I had a friend change my processor number from one to four. I thought this was making my computer work much harder and making it overheat, but thats because i was on a bed. I found that out after i changed it back to one, and now i cannot change it back to four processors. It only displays one of them. If anybody has a solution to this, i would appreciate it sooo much. Please help. My computer is very slow now.

Hello Stephena,

No worries. If you uncheck the Number of processors box and apply, Windows 7 will use all processors/cores by default.

 

[OvenMaster]

I wish I could remember specifically where I found the info, but I do remember reading a while ago that checking the box to use all processor cores in XP, Vista and 7 had a slight but definite positive impact during bootup.

When I installed XP and 7, and then enabled all cores, my bootup and loading times were shaved by a few seconds. Not a huge improvement, but measurable nonetheless.

My two centavos.

 

[Brink]

Hello Tom,

That may just be either a placebo effect, or something else that could be the cause of the slight improvement.

Whether unchecked (recommended) or checked and all selected, it will use the same all processors/cores, so it shouldn't make any difference.

 

[diplo]

I know this article is a tad old, but I thought I would share this link:

Tweaking Myth: Decrease boot time with msconfig — Within Windows

The placebo effect is powerful