To upgrade to Windows 8.1, the processor needs to be able to run NX or XD for security purposes.  This supposedly can viewed and changed by accessing the BIOS, clicking on the SECURITY tab.  Then the nx or xd can be turned on if the option exists.  I run BIOS AO3.  I have tried hitting F2 and F12 and I do get into the BIOS, but there is no "security tab" to click on.  What am I doing wrong?