VirtualBox Issue: "Create Virtual Machine" wizard only shows 32 bit guest versions in "Version" dropdown

Recently I have came across very strange problem while creating Virtual Machine(VM) using Oracle VM VirtualBox.I was planning to install the 64 bit CentOS as the Guest OS on my 64 bit Windows Host but the Version drop-down in the Create Virtual Machine wizard didn't have any 64 bit options. Through VirtualBox documentation, I have checked the details of supported Host OS & Guest OS and found that it also supports 64 bit Guest OS. Therefore it's a problem with my system configuration. 

In this "How To" guide, we would discuss how to resolve the above issue so that if you face the similar issue then you could also easily troubleshoot the issue.

Depending upon the Host OS, Host OS Version and type of processor (Intel or AMD), the solution might vary but it is advised to check both the options that we are about discuss now.
To resolve the issue, check if below conditions are met:

• Turn Off (uncheck) the Hyper-V feature using Turn Windows features on or off dialogue box. Use the windows search box and search "Turn Windows features on or off" to launch the Turn Windows features on or off dialogue box. Unchecking the Hyper-V feature, will prompt to restart the the system to apply this changes.
  
  
  
• Enable the Hardware Virtualization features from BIOS.
  Techniques and options for enabling hardware virtualization from BIOS may differs for Intel and AMD processors. Intel named its technology VT-x; AMD calls theirs AMD-V.
  • For Intel based processor, both Intel Virtualization Technology & Intel VT-d  Feature should be enabled in the BIOS. 
  • For AMD based processor, haven't got chance to check. 😉 Help me here!
    
    For Reference, see the below screenshots:
  
  
  
  

That's it ! Now you can see the 64 bit Guest versions in the Version drop-down.

 Disclaimer:
I have tried this in two different windows systems having Intel processor but different Windows OS. The solution for both the systems slightly varies and described below:

• System 1 : Lenovo ThnikPad having below specification
• System Type: 64-bit Windows 10, x64 -based processor 
• Processor: Intel(R) Core(TM) i5
• VirtualBox Version 5.1.24 r117012 (Qt5.6.2)
Solution: Have to Turn Off the "Hyper-V" feature using "Turn Windows features on or off " dialogue box and enable both the options in the BIOS i.e. "Intel Virtualization Technology" & "Intel VT-d  Feature".
• System 2 : Sony Vaio E Series having below specification
• System Type: 64-bit Windows 7 Home Basic
• Processor: Intel(R) Core(TM) i3
• VirtualBox Version 5.1.24 r117012 (Qt5.6.2)
Solution: Haven't found any option of "Hyper-V" feature in "Turn Windows features on or off" dialogue box. Don't remember exactly but there was only one option in the BIOS i.e. either "Intel Virtualization Technology" or "Intel VT-d  Feature" to enable the hardware virtualization.

Thank you for reading this article. If you came to know what specific options should be enabled for AMD processor in BIOS in order to enable the hardware virtualization, do let me know in the comment box. I will add those in this article. Happy Learning!!