Enable vt-x on Studio 1555

Hello everyone,

I have a Studio 1555 with p8600 processor and want to enable the vt-x extension to use 64 bit version of fedora on virtualbox. I have the bios version A06 and enabled the virtualization extension under the bios advanced menù, but when I try to load a 64 bit virtual machine it seems that the extionsion is not enabled.

Do you have a suggestion to verify if is it enabled? Maybe I may upgrade my bios version to the last A12.