I tried confirming it with the Coreinfo.exe tool. Here is the output of that tool:
Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz
Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
HYPERVISOR * Hypervisor is present
VMX - Supports Intel hardware-assisted virtualization
EPT - Supports Intel extended page tables (SLAT)
The output indicates that virtualization is not available (note the -
next to VMX), but another Hypervisor is present.
It turns out Hyper-V is that other Hypervisor. I un-installed Hyper-V and the Coreinfo.exe tool now gives the following output:
Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz
Intel64 Family 6 Model 42 Stepping 7, GenuineIntel
HYPERVISOR - Hypervisor is present
VMX * Supports Intel hardware-assisted virtualization
EPT * Supports Intel extended page tables (SLAT)
I un-installed Hyper-V and VirtualBox now detects the hardware virtualization support from the BIOS (and x64 guest OSs can now run).
EDIT
According to the VirtualBox help you should not run multiple Hypervisors on the same machine. Would love to see VirtualBox actually warn you that this is the reason why x64 guests cannot run. Would save allot of time!