Hot-Plug CPU and RAM failure – Windows 2008

After adding CPU and RAM to a Windows 2008 R2 instance, the instance does not recognize the added resources.

Cause

Hot-plug CPU is only supported on Datacenter and Itanium versions, and hot-plug RAM is only supported on Datacenter, Itanium and Enterprise versions. Hot-plugging CPU may cause the instance to be seen as “unresponsive” if the Kernel-Mode Driver Framework is below version 1.11.

Solution

Reboot the instance, and it will recognize the added resources; or, use one of the hot-plug-supported editions of Windows 2008 R2. Before hot-plugging CPU, install Kernel-Mode Driver Framework 1.11