[Notebook] How to enable or disable Intel® Virtualization Technology (VT-x)?

With a VT-x supported Intel® Processor and a VT-x supported Bioses, VT-x can be "Enabled" or "Disabled" in Bioses. (The default of this item is Enabled in Bioses)

About how to enter Bioses setup menu, please click here.

  
If the "Intel Virtualization Technology" is grayed out and cannot be changed, please set “Intel Trusted Execution Technology” to “Disabled” first①. 

Then you can configure the “Intel Virtualization Technology” settings according to your preferences②.

How can I tell whether Intel® Virtualization Technology (VT-x) is enabled or disabled in my system?

You can use the Intel® Processor Identification Utility to verify whether your system can support Intel® Virtualization Technology.

Use this tool, and select the CPU Technologies tab. Check whether the Intel® Virtualization Technology options are checked or not.

Here is an example to show that the Intel® Virtualization is available.

Here is an example to show that the Intel® Virtualization is not available.

If Intel® Virtualization Technology is not checked in the tool, your processor might be able to still supports Intel® Virtualization Technology because it is already being used by some other software which uses a Hypervisor.

In that case, you can also use the Task Manager to verify the situation.

Here is an example to show Intel® Virtualization is enabled by using Task Manager:

From the table below, you can check if your processor supports Intel® Virtualization, whether it is disabled, and other additional information.

Most of above information is excerpted from Intel official website. You can also refer to below link for more infromation:
http://www.intel.com/content/www/us/en/support/articles/000005486/processors.html