Here is the way I did it. Go into your BIOS probably by hitting the 'delete key' at boot up.
Choose the option that allows you to see the drives you have installed, probably the first one in the BIOS. The drive options here will most likely be set to 'Auto' use the 'up' 'down' keyboard keys to scroll down to your HDD and when it is highlighted press 'Enter' on your keyboard and it should change to user from auto and the HDD info will be shown. Mine was 16 logical heads.