Intel i5-4210u processor - 64bit guest support

[marius_roma]

I have an AsusPro notebook with an Intel Core i5-4210U CPU running Windows 8.1 64 bit.
I installed VirtualBox 4.3.30 but I am unable to create 64bit guest VMs.
Virtualization is enabled in BIOS.
What else can I check/set in order to create 64bit guest VMs?
Regards
marius

[Perryg]

FAQ: I have a 64bit host, but can't install 64bit guests.