Run "msconfig" and go to the boot tab. Select "Advanced options." If "Number of processors" is checked, uncheck it. If it is unchecked, check it and selecet the correct number of processors (threads) if the option is available. If the right number is not available, then it is likely that your BIOS needs updating (which you did), your BIOS settings may have a certain number of cores disabled or (most likely) you need to re-install Windows.