When trying to create a Virtualbox VM recently I was only presented with the option of creating a 32-bit client. After a bit of research it turns out this can be caused by incorrect settings in the BIOS or by a competing Virtual Machine software cohabiting the system.

CPU

First of all your CPU must support the virtualization extensions. We can check this on a Bash console if you have installed the integrated feature.

$ egrep -c '(vmx|svm)' /proc/cpuinfo
2  

If it returns a positive number, 1 or higher your CPU does support the virtualization extensions. You must still ensure it's enabled in the BIOS. If it returns 0 then your CPU does not support hardware virtualization.

BIOS

You must have hardware virutalization enabled in the BIOS to create and run 64-bit virtual machines.

The following BIOS features need to be enabled:

  • Intel Virtualization Technology [Enabled] (or AMD-v).
  • Intel VT-d Feature [Enabled].

Hyper-V

If Hyper-V is enabled then Virtualbox will not be able to create 64-bit virtual machines.

Start > type "Turn Windows features on or off" > ensure Hyper-V is unchecked  

Turn Windows features on or off

If Hyper-V was enabled this will require a reboot.

References