In my BIOS there are 3 operating options - 'Power Saver', 'Normal' and 'Performance' (which is referred to as 'ASUS Optimal Mode' in the manual). I selected Performance and the motherboard changed the following:
CPU ratio 103
Multiplier 42x
Target Turbo Mode Frequency = 4.3GHz (103x42)
DRAM frequency 1648MHz
DRAM voltage 1.5V
CPU voltage 1.160V (offset)
VVCIO voltage 1.059V
CPU PLL 1.796V
PCH voltage 1.075V
Assuming that because the BIOS has made these changes itself once I selected Performance it's all going to run fine? I can easily go back if not.
I did some Googling and apparently it's stable to use - we'll see how I get on with it.