Enable 64-bit VirtualBox? Step-by-Step Fix

To enable 64-bit guests in VirtualBox, you must turn on hardware virtualization (VT-x/AMD-V) in your computer’s BIOS/UEFI and ensure the 64-bit guest OS is selected in the VM settings. If the 64-bit option is greyed out, it is almost always because virtualization is disabled in firmware, not because of VirtualBox itself.

Why 64-Bit Options Disappear in VirtualBox

VirtualBox relies on the host CPU’s virtualization extensions to run 64-bit operating systems. These extensions—Intel VT-x and AMD-V—are disabled by default on many desktops and laptops. When they are off, VirtualBox hides all 64-bit guest options, even if your processor is fully capable. This is a common source of confusion: users see a 64-bit CPU but only 32-bit choices in the New Virtual Machine wizard.

Another cause is running VirtualBox inside another virtual machine (nested virtualization). If your host is itself a VM, the hypervisor must expose VT-x/AMD-V to the guest, which is not always enabled. Similarly, some Windows security features like Core Isolation or Hyper-V can conflict with VirtualBox’s ability to use hardware virtualization, though this usually prevents the VM from starting rather than hiding 64-bit options.

Check Your CPU and Host OS Support

Before changing settings, confirm your hardware actually supports virtualization. Most Intel and AMD processors from the last 15 years do, but some budget or older models do not. On Windows, open Task Manager > Performance > CPU and look for “Virtualization: Enabled” or “Disabled.” On Linux, run grep -E "(vmx|svm)" /proc/cpuinfo—if you see vmx (Intel) or svm (AMD), your CPU supports it. On macOS, check System Information > Hardware > “Virtualization” (though macOS hosts rarely have this issue).

Your host OS must also be 64-bit. A 32-bit operating system cannot run a 64-bit guest, regardless of the CPU. If you have a 32-bit Windows or Linux installed, you need to reinstall a 64-bit version to see 64-bit guest options.

Enable Virtualization in BIOS/UEFI

This is the most common fix. The exact menu names vary by motherboard, but the steps are similar:

1. Restart your computer and press the key to enter BIOS/UEFI setup—commonly Del, F2, F10, or Esc (check your motherboard manual or the splash screen).
2. Look for a section called Advanced, CPU Configuration, Security, or Overclocking.
3. Find a setting named Intel Virtualization Technology, VT-x, AMD-V, SVM Mode, or Virtualization Extensions.
4. Set it to Enabled.
5. Save and exit (usually F10), then boot into your OS.

On some newer systems, the setting might be under Advanced > Processor or System Configuration. If you cannot find it, search online for your specific motherboard or laptop model plus “enable VT-x” to get the exact path.

Create a New 64-Bit Virtual Machine

Once virtualization is enabled in BIOS, restart VirtualBox completely (close and reopen it). Then create a new VM:

1. Click New.
2. Give the VM a name and set the Type and Version. The Version dropdown will now show both 32-bit and 64-bit options, e.g., “Ubuntu (64-bit)” or “Windows 10 (64-bit).”
3. Select the 64-bit version and continue.
4. Allocate memory and create a virtual hard disk as usual.

If you already created a 32-bit VM and want to switch to 64-bit, you cannot simply change the OS type in settings—the architecture is fixed at creation. You must create a new VM and install the 64-bit OS from scratch.

When 64-Bit Still Doesn’t Appear

If you enabled virtualization and still see only 32-bit options, try these steps in order:

• Check for Hyper-V or Core Isolation: On Windows, Hyper-V and Memory Integrity (Core Isolation) can interfere. Open “Windows Features” and uncheck Hyper-V, then disable Core Isolation in Windows Security > Device Security > Core Isolation. Restart.
• Update VirtualBox: Very old versions may not recognize newer CPUs. Install the latest version from the official site.
• Check for nested virtualization: If you are running VirtualBox inside a VM (e.g., on a cloud service or another hypervisor), enable “Nested Virtualization” in the host VM settings if available.
• Reset VirtualBox configuration: Sometimes a corrupted config file causes issues. Close VirtualBox, back up and delete the ~/.config/VirtualBox (Linux) or %USERPROFILE%\.VirtualBox (Windows) folder, then reopen VirtualBox.

If none of these work, your CPU may genuinely lack virtualization support—check the exact model on the manufacturer’s website.

Common Misconceptions

Many users assume that a 64-bit guest requires a 64-bit host OS, which is true, but they also assume that a 64-bit host automatically allows 64-bit guests. That is false—the BIOS setting is the gate. Another misconception is that VirtualBox itself is 32-bit and therefore cannot run 64-bit guests. VirtualBox is a 64-bit application on 64-bit hosts, and even the 32-bit version of VirtualBox can run 64-bit guests if the host OS and CPU support it (though this is rare and not recommended).

Some users try to force the issue by editing the VM’s .vbox file to change the OS type to a 64-bit variant. This does not work reliably because the guest OS installation media must match the architecture. Even if you trick the settings, the 64-bit installer will fail to boot without hardware virtualization.

Performance Considerations

Once you have a 64-bit VM running, you should allocate at least 2 GB of RAM for a modern 64-bit OS, and 4 GB or more for Windows 10/11 or a heavy Linux desktop. Enable PAE/NX in the VM settings if you want to use more than 4 GB of RAM in a 32-bit guest, though a 64-bit guest is a better solution. Also, install the VirtualBox Guest Additions inside the guest to get better video performance, shared folders, and seamless mouse integration.

If you are running a 64-bit guest but performance is poor, check that the VM is set to use at least two CPU cores (if your host has them) and that hardware acceleration is enabled (Settings > System > Acceleration > “Enable VT-x/AMD-V”).

Frequently Asked Questions

Why is the 64-bit option greyed out in VirtualBox?

The most common reason is that hardware virtualization (VT-x/AMD-V) is disabled in the BIOS/UEFI. Enable it in firmware settings, then restart VirtualBox. Other causes include a 32-bit host OS, Hyper-V enabled on Windows, or running VirtualBox inside a VM without nested virtualization.

Can I enable 64-bit in an existing 32-bit VM?

No. The architecture is set when the VM is created. You must create a new VM with a 64-bit OS type and install the 64-bit guest from scratch.

Does VirtualBox support 64-bit guests on a 32-bit host?

No. A 32-bit host OS cannot run a 64-bit guest because the guest kernel requires 64-bit CPU mode, which the host OS does not provide. You need a 64-bit host OS.

How do I check if my CPU supports virtualization?

On Windows, open Task Manager > Performance > CPU and look for “Virtualization.” On Linux, run grep -E "(vmx|svm)" /proc/cpuinfo. On macOS, use System Information > Hardware. If it says disabled, you need to enable it in BIOS.

Will enabling VT-x slow down my computer?

No. Enabling VT-x/AMD-V in BIOS does not affect normal performance. It only allows the CPU to handle virtualization instructions more efficiently, which is beneficial when running VMs.

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