The follow the same guide for your current hardware?
I believe the trick to unlocking all Gigabyte BIOS goodies is Ctrl+F1. Beyond that, you're still using Core 2 Due hardware, so I'm going to go out on a limb and guess that it's reasonably similar? Sure, stuff in the BIOS might have slightly different names, but nothing the manual cannot sort out.
Trust me. Give it a try.