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.

Francois Nel

Posted 2013-11-12T12:19:04.233

Reputation: 271

See also this answer: http://superuser.com/a/700414/84776

– steenhulthin – 2014-06-20T10:07:14.803

This is a known limitation of having Hyper-V installed. This is pretty much the same reason you cannot have VMWare installed and enable Hyper-V. – Ramhound – 2013-11-12T12:26:19.527

@Ramhound yes well, I did not know that it is such a "known limitation". See my edit to my answer.

– Francois Nel – 2013-11-12T12:59:49.060

Answers

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!

Francois Nel

Posted 2013-11-12T12:19:04.233

Reputation: 271

Well I have the same problem and coreinfo says [HTT * Hyperthreading enabled] [HYPERVISOR - Hypervisor is present] [VMX * Supports Intel hardware-assisted virtualization] [SVM - Supports AMD hardware-assisted virtualization] [X64 * Supports 64-bit mode]. I have VirtualBox 4.3.15 r95713 and no VirtulPC or VMWare installed, is just virtualbox. So not sure how to fix it. – RaduM – 2014-09-07T09:00:22.420

Just to clarify on how to uninstall Hyper-V: 1. follow this guidance (opening the control panel on Win 8 works different though) to open the "Windows features" dialog. 2. Deselect Hyper-V. 3. Restart your PC (as requested by Windows). 4. Done.

– ComFreek – 2014-05-06T15:46:52.170

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!

BuLLHACK

Posted 2013-11-12T12:19:04.233

Reputation: 156

I was messing around resetting the BIOS, disabling and enabling VT. Searching widely on the motherboard and cpu for a solution. And it was the damn Hyper-V not playing nice. – Wolf5 – 2014-07-08T19:00:02.533