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I've just got a new Dell Vostro 470 with a quad core (8 threads) i7 3770 and I'm trying to run virtual machines on it, which works fine, except if I want to assign multiple cores to a VM. I've checked the bios which states Intel Virtualization Technology [Enabled], but both Hyper-V and VirtualBox will only allow me to assign a single core.

If I run the Intel Processor Identification Utility on the host OS it tells me that Intel Virtualization Technology isn't supported by the processor, but according to the Intel website, it is.

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So whats going on? Have Dell clipped the i7's wings? Is there some config in Windows I need to change?

Greg B
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4 Answers4

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After some more Googling last night I got a lead that it might be a limitation of Windows 8 Client Hyper-V.

Here's a guy having issues with two OS's reporting different VT-x values.
This SuperUser question put me on to the idea that Client Hyper-V has some hard limitations.

This morning I've uninstalled Hyper-V from the "Turn Windows features on or off" in control panel. After a reboot VirtualBox allows me to assign multiple cores to a VM. It appears Windows 8 Client Hyper-V is the culprit.

From what I can tell Windows 8 Client Hyper-V dissables VT-x at the OS level, so applications running on top of Windows, including other virtualization products and the Intel Processor Identification Utility, incorrectly report that VT-x isn't available.

Community
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Greg B
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3

Hyper-v takes exclusive control of the vt-x feature.

To disable it, you need to either

  1. remove hyper-v or

  2. disable hyper-v using vt-x (which renders hyper-v unusable until you revert the setting)

For 2), bcdedit /set hypervisorlaunchtype off
to undo bcdedit /set hypervisorlaunchtype on or bcdedit /set hypervisorlaunchtype auto

Nifle
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mathew
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Have you checked that virtualization is enabled in BIOS?

Typically it is located under "Advanced BIOS features" as "Virtualization Technology". See this page for more instructions: http://www.sysprobs.com/disable-enable-virtualization-technology-bios

For dell-specific instructions on enabling virtualization, see "How to Enable VT on a Dell for VMware"

jsalonen
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This is a know Windows 8 problem.

People who reinstall say everything works. See link.

A fun reason might be that VT-x support needs to be detected during OS install, and some models of the Dell Vostro don't include VT-x support. Hence, when the install image was made by the OEM (Dell) there was no VTx support.

Another explanation is that there is a bug in the BIOS, and flashing the bios may help enforce the state of this value.

You should reinstall.

edit

A common problem comes from the android sdk's Intel emulation persistently using a VT-x slot. Did you install the android sdk?

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Mikhail
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