Enable Multiple Cores on Windows 7

Posted September 12, 2011 by Aaron St. Clair in Windows 7

Many games and other processor-heavy applications really require the CPU power of multiple cores. However, even if you have a dual, quad, six-core processor, you are not guaranteed that all of them are always turned on. By default, Windows will run all your cores. However, in some circumstances windows will set your active cores lower than the max. Problems arise when the Windows OS then never re-enables all the cores. If you have experienced a drastic slowdown in system performance, this could be your quick fix.

In some circumstances Windows 7 will disable certain cores. Often this is to save in power consumption or to assist older programs in working correctly. Problems arise when the OS disables a core in error or has difficulty enabling the core again.

Go to Start and type msconfig.exe. Run the program as Administrator.


Click the Boot tab and choose Advanced Options.

Boot - Advanced Options

Check the box labeled Number of processors. Pick from the list how many cores you want to run. Click Ok.

Number of Processors

Note: If you number of processors is incorrectly displayed or disabled, try ticking detect HAL in the BOOT Advanced Options in msconfig and then rebooting first.

Click Ok again.


Click Restart.



About Aaron St. Clair

Aaron St. Clair is a tech guru studying Computer Science at Appalachian State University in Boone, North Carolina. When he's not tinkering with new gadgets, modding systems, or slaving away at the mercy of the Tech-Recipe overlords, you can find him exploring the high country.
View more articles by Aaron St. Clair

The Conversation

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  • Anand Tulpule

    “try ticking detect HAL in the BOOT Advanced Options in msconfig”
    Not available here and on my system as well.

  • Recoil

    Same here no dectect HAL and i cant see it in you screen dumps.

  • Lars Nielsen

    Hello Aaron,
    What version of Windows 7 are you using? I’m having a Home Premium version and, it looks different from what you are showing. I got an Intel i5- 650 CPU with 2 cores, but only one shows up under “No. of prrecessors” and there is apparently no way I can change this and no display gives me any possibility for choosing. Thre is no where I can check “detect all”.
    Have you got any suggestions?

    • Hmm that’s a good question. I’ve changed OS maybe 5 times since then… I’m pretty sure it was either W7 Professional or W7 Ultimate. I do remember that there was an issue with Home Premium, though I’m fuzzy on what the exact issue was. I looked up your CPU, and found that it does have hyperthreading, which took my only real idea away… A CPU has to have hyperthreading for this to work, as it really enables virtual cores. Try running CPUz and seeing if it shows two cores being used. If so then by default the OS has them enabled.

  • Andy Fox

    What happens when u don’t restart?