x64 Hardware Virtualisation support not detected on Windows 8.1

I get the following error (and yes I know this has been reported many times, but please read further): VT-x/AMD-V hardware acceleration is not available on your system. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot.

The issue is that Virtualisation is enabled in my BIOS and I also made sure my BIOS is upgraded to the latest version.

Here is the thing: I used VirtualBox on the same machine, but with Windows 7 and I could run exactly the same x64 guest images.

Solution 1:

All what you need is disabling Hyper-V. Run command prompt with administrator rights and run the following command:

bcdedit /set hypervisorlaunchtype off

Restart your PC and you're done!

Solution 2:

I tried confirming it with the Coreinfo.exe tool. Here is the output of that tool:

Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz
Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
HYPERVISOR      *   Hypervisor is present
VMX             -   Supports Intel hardware-assisted virtualization
EPT             -   Supports Intel extended page tables (SLAT)

The output indicates that virtualization is not available (note the - next to VMX), but another Hypervisor is present. It turns out Hyper-V is that other Hypervisor. I un-installed Hyper-V and the Coreinfo.exe tool now gives the following output:

Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz
Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
HYPERVISOR      -   Hypervisor is present
VMX             *   Supports Intel hardware-assisted virtualization
EPT             *   Supports Intel extended page tables (SLAT)

I un-installed Hyper-V and VirtualBox now detects the hardware virtualization support from the BIOS (and x64 guest OSs can now run).

EDIT According to the VirtualBox help you should not run multiple Hypervisors on the same machine. Would love to see VirtualBox actually warn you that this is the reason why x64 guests cannot run. Would save allot of time!