Modern CPUs include hardware virtualization features that help accelerate virtual machines created in VirtualBox, VMware, Hyper-V, and other apps. But those features aren’t always enabled by default.

Virtual machines are wonderful things. With virtualization apps, you can run an entire virtual computer in a window on your current system. Within that virtual machine, you can run different operating systems, test apps in a sandbox environment, and experiment with features without worry. In order to work, those virtual machine apps need hardware acceleration features built into modern CPUs. For Intel CPUs, this means Intel VT-x hardware acceleration. For AMD CPUs, it means AMD-V hardware acceleration.

At some point, you may encounter error messages in your VM apps like the following:

  • VT-x/AMD-V hardware acceleration is not available on your system
  • This host supports Intel VT-x, but Intel VT-x is disabled
  • The processor on this computer is not compatible with Hyper-V

These errors can pop up for a couple of different reasons. The first is that the hardware acceleration feature may be disabled. On systems with an Intel CPU, the Intel VT-x feature can be disabled via a BIOS or UEFI firmware setting. In fact, it’s often disabled by default on new computers. On systems with an AMD CPU, this won’t be a problem. The AMD-V feature is always enabled, so there’s no BIOS or UEFI setting to change.

The other reason these errors can pop up is if you’re trying to use a virtualization app like VMWare or VirtualBox when you already have Microsoft’s Hyper-V installed. Hyper-V takes over those hardware acceleration features and other virtualization apps won’t be able to access them.

So, let’s take a look at how to fix these issues.

Try Uninstalling Hyper-V

If you have Hyper-V installed, it gets greedy and won’t let other virtualization apps access hardware acceleration features. This more often happens with Intel VT-x hardware, but can also happen with AMD-V on occasion. If this is the case, you’ll see an error message in your virtualization app to the effect that Intel VT-x (or AMD-V) is unavailable, even though it is enabled on your computer.

To solve this problem, you just need to uninstall Hyper-V. Hyper-V is an optional Windows feature, so uninstalling it is a little different than uninstalling a regular app. Head to Control Panel > Uninstall a Program. In the “Programs and Features” window, click “Turn Windows features on or off.”

In the “Windows Features” window, clear the “Hyper-V” checkbox and then click “OK.”

When Windows is done uninstalling Hyper-V, you’ll need to restart your PC and then you can try using VirtualBox or VMware again.

Turn Intel VT-x On in Your BIOS or UEFI Firmware

If you have an Intel CPU and uninstalling Hyper-V didn’t solve your problem—or your virtualization app reported that Intel VT-x was disabled—you’ll need to access your computer’s BIOS or UEFI settings. PCs made prior to the release of Windows 8 probably use BIOS. PCs made after Windows 8 came out may use UEFI instead, and the likelihood of using UEFI grows the more modern the PC.

On a BIOS-based system, you’ll access BIOS settings by restarting your PC and pressing the appropriate key right when it first boots. The key you press depends on your PC’s manufacturer, but it’s often the “Delete” or “F2” key. You also will most likely see a message during startup that says something like “Press {Key} to access setup.” If you can’t figure out the right key to get into your BIOS settings, just perform a web search for something like “{computer} {model_number} access BIOS.”

RELATED: What You Need to Know About Using UEFI Instead of the BIOS

On a UEFI-based computer, you can’t necessarily just press a key while the computer is booting. Instead, you’ll need to follow these instructions to access the UEFI firmware settings from the Windows advanced startup options. Hold down the Shift key as you click Restart in Windows to reboot straight to that menu.

Whether your PC uses BIOS or UEFI, once you’re in the settings menu, you can begin looking around for an option labeled something like “Intel VT-x,” “Intel Virtualization Technology,” “Virtualization Extensions,” “Vanderpool,” or something similar.

Often, you’ll find the option under a “Processor” submenu. That submenu may be located somewhere under a “Chipset,” “Northbridge,” “Advanced Chipset Control,” or “Advanced CPU Configuration” menu.

Enable the option and then select “Save and Exit” or the equivalent feature to save your settings changes and reboot your PC.

After the PC restarts, you can try using VirtualBox or VMware again.

What to Do If You Don’t See the Intel VT-x Option in BIOS or UEFI

Unfortunately, some laptop manufacturers and motherboard manufacturers don’t include an option in their BIOS or UEFI settings for enabling Intel VT-x. If you don’t see the option, try performing a web search for the model number of your laptop—or your motherboard, if it’s a desktop PC—and “enable Intel VT-x”.

RELATED: How to Check Your Motherboard Model Number on Your Windows PC

In some cases, manufacturers may later release a BIOS or UEFI firmware update that includes this option. Updating your BIOS or UEFI firmware might help—if you’re lucky.

And, remember—if you have an older CPU, it may not support the Intel VT-x or AMD-V hardware virtualization features at all.

Image Credit: Nick Gray on Flickr

Profile Photo for Chris Hoffman Chris Hoffman
Chris Hoffman is Editor-in-Chief of How-To Geek. He's written about technology for over a decade and was a PCWorld columnist for two years. Chris has written for The New York Times and Reader's Digest, been interviewed as a technology expert on TV stations like Miami's NBC 6, and had his work covered by news outlets like the BBC. Since 2011, Chris has written over 2,000 articles that have been read more than one billion times---and that's just here at How-To Geek.
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