Enable Virtualization on Dell Optiplex 755 to run Oracle VirtualBox 4

Recently I ran into an issue when working on creating a test cluster environment for Windows 2008 R2 with Oracle VirtualBox running on Fedora 16 64 bit on a Dell Optiplex 755.

The issue was VirtualBox would complain about VT-x/AMD-V not being enabled and would stop the VM from loading. After doing some digging around found that there is a specific setting in the BIOS to enable what is needed to enable the settings for 64 bit  VM’s to run. These changes will also work in enabling Hyper-V to run properly on Windows systems.

To fix this, boot the computer and press F2 to enter the BIOS.

In the BIOS you need to change the following settings

Security > Execute Disable (set to On)
Performance > Virtualization (set to On)
Performance > VT for Direct I/O Access (set to On)
Performance > Trusted Execution (set to Off)

Save and exit the BIOS, then power the computer down. it is important that the system be powered down.

After the system was powered up, the VM started properly with 64 bit support.

16 Responses to “Enable Virtualization on Dell Optiplex 755 to run Oracle VirtualBox 4”

  1. Doug says:

    This works like a charm, many thanks

  2. Prasad says:

    Many thanks – this worked perfect!

  3. Tommy says:

    Worked for me too – thanks!! I am installing Windows 8 Demo using VirtualBox 4.1 on Ubuntu

  4. Vincent Voyer says:

    Another happy dev fixed his problem with your solution. Thank you!

  5. Tim says:

    Worked for my 755! Thanks!

  6. Jeff C says:

    Worked for me to get VMWare Player 7.0 working! I thought I knew what to turn on but it turns out that Trusted Execution must be off.

  7. bilal says:

    i have dell 755 e4600intel processor i cant enable virtualization on my pc plz help me above method is not affective for my case

    • huge says:

      Dell Optiplex 755 Core 2 Duo E4*** no virtualization. e6xxx has.

      • Fatih says:

        I have a 745 with Pentium D 930, but i don’t have the “Performance > Virtualization” in my BIOS.

        Can you pls help me?

        BIOS Update to Version 2.6.6

        • newlife007 says:

          It is possible it is not supported with that model of Dell. The Pentium D 930 supports Intel VT-x but that is all it supports so the bios for the Dell may not have it. I cannot find any manuals on the screens available for the 745 and I do not have that model readily available to me.

  8. Byron Injeeli says:

    Good info, thumbs up.

  9. ALI MANSHA says:

    Thanks A lot
    Good Information
    Problem Fixed

  10. Chuck says:

    I’ve enabled all those things in bios but kvm-ok still says “your cpu supports virtualization… is disabled by your bios.” I cannot figure out why. Anyone else having this issue? Any insights?

    • newlife007 says:

      I have checked my Dell Optiplex 755 with Intel Core 2 Duo E6550 and I have the following set for VirtualBox 5 to run. I have not tried this with KVM but it should be the same.

      Security > Execute Disable (set to On)
      Security > TPM Security > Off
      Performance > Virtualization (set to On)
      Performance > VT for Direct I/O Access (set to On)
      Performance > Trusted Execution (set to Off)

  11. Ahsan says:

    Great, Thanks


  1. Ubuntu:No option for 64-bit OS VirtualBox guest OS in Ubuntu 14.10 Dell OptiPlex 755 – Ubuntu Linux Questions - […] Thanks to the article that pinpoited exact issue with bios on dell optiplex755 […]

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