When you run the -install command, PNPCPU does the following:
Installs the bus enumerator driver.
Marks all existing processors with problem code 28 - visible in the Device Manager.
Adds ONECPU to the Boot Configuration Data (BCD) settings.
Saves the number of processors that Windows is using when -install is run.
Pre-installs the INF file for the processor driver.
After the installation is completed, you will see the following message:
Enabled hot add cpu... Please reboot the system before proceeding with the test
Restart the system either by executing shutdown from the command line, or from a system menu option.
After you restart your computer, Windows will only be using one logical processor. You can confirm this in Device Manager by finding processors with error code 28.