Asus Crosshair V Formula/ThunderBolt - Manual (Page 106)

3-22 Chapter 3: BIOS setup
3.5.5. CPU.Core.On/.Off.Function
ASUS.Core.Unlocker.[Disabled]
Allows you to enable ASUS Core Unlocker to get full computing power of
processor.Configuration options: [Disabled] [Enabled]
System might become unstable due to different CPU margins.
CPU.Core.Activation.[Auto]
Allows you to manually turn off the second or the third core.
Configuration options: [Auto] [Manual]