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I had a VM with two cores. I powered it down and changed the settings to four cores.

Here's what I see:

  • System (right-click on My Computer > Properties) reports "(2 processors)"
  • Task Manager shows two CPU core graphs
  • Device manager shows four CPUs under Processors
  • VMWare reports four CPUs

It seems strange. Am I missing some step to get Windows to use the remaining two CPUs?

I'm running Windows 7 SP1 x64.

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  • What EXACT version of Windows are you using?
    – Chopper3
    Mar 5, 2013 at 18:35
  • And what Edition of which Version are you running?
    – joeqwerty
    Mar 5, 2013 at 18:38
  • Windows 7 Professional SP1.
    – ashes999
    Mar 5, 2013 at 19:02

3 Answers 3

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You've give the VM 4 CPU's, Windows 7 will only deal with two physical CPUs, it'll see more but it's a client OS so only handles 2 at a time.

What you need to do is force it to think it's one CPU with four cores, by the way VMWare Workstation lets you define this on a per-VM basis as it's designed to Client OS based VMs, whereas ESXi is more focussed on the Server related OSs which can handle >2 physical CPUs.

Here's a hack/change to do what you need;

http://www.yellow-bricks.com/2009/06/04/per-processor-licenses-for-your-application/

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  • This worked with a value of 4.
    – ashes999
    Mar 5, 2013 at 20:45
  • Fun fact: this also seems to be an issue in Workstation (12 at least), if you happen to try to change core number from a running VM "on the fly". numvcpus is increased properly, but cpuid.coresPerSocket doesn't get set accordingly.
    – mirh
    Mar 16, 2020 at 13:03
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Most of VMware machines you will find are configured to work with the last free version of VMware Workstation, namely 6. The latter means you have 2 processors limitation. In case you have a license for VMware 6.5+ you can change "hardware compatibility" (as VMware calls it), so that you can add more processors.

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Also make sure you're explicitly setting it in esxi as 2cpu's 2cores each. that will be important as, like the previous poster indicated, windows 7 can't handle more than two cpu's.

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