Windows Server 2008 R2 as Guest in VirtualBox

Windows Server 2008 R2 only comes in an x64 flavor. To install this in VirtualBox as a guest OS you need to enable the VT-x/AMD-V options in the VM settings dialog. You also need to make sure you have an x64 compatible CPU and that you enable Virtualization support in your BIOS settings.

I had all this done, but whenever I started the VM guest with the Server 2008 R2 ISO mounted, VirtualBox would give me an error saying:

"VT-x/AMD-V hardware acceleration has been enabled, but is not operational. You 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot.
Please ensure thet you have enabled vt-x/AMD-V propert in the BIOS of tour host computer."

I was installing this on a Dell Optiplex 755 with an Intel E8400 which does support x64. My BIOS was revision A12 and already had the Virtualization, VT for Direct I/O and Trusted Execution features turned to On. I tried cold booting and rebooting a couple of times but VirtualBox kept giving me the same error.

What eventually worked was to turn all those features off, restart by turning power off and on, then turn Virtualization and VT for Direct I/O to On but leave Trusted Execution to off. Also, TPM was set to Off in Security.

Went back to my Win7 host, started VirtualBox and this time the Win Server 2008 VM started without issue. Completed the install without problem.

Oh, and you may also need to change the VirtualBox Network Adapter type to Intel PRO/1000 MT Server, and the Sound Controller to Sound Blaster 16 in the VM settings dialog. Otherwise Windows Server 2008 won't detect drivers for the default network card and sound (apparently there are no 64bit drivers for the PCNet Ethernet Controller or the ICH AC97 Sound Controller).


  1. Thank you - I spent a lot of time trying different things and your post did the trick for me and my Dell Optiplex 960.

  2. Doesn't work once you run DCPROMO and make a domain controller.


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