what does these do? and how to determine what to use???
CPU Volt Reference: 0.63x
CPU PLL volt: 1.6
FSB termination volt: 1.40
NB voltage: 1.40...suggestion for 3600Mhz and up that is safe
NB voltage reference: 0.67x
SB voltage: 1.05
Only going by DFI experience here.

Firstly the default CPU VOLT ref I presume is the same as GTL ref and should be 0.67x for a quad core chip. Not set in stone though.

FSB and NB on the DFI required around 1.55v for decent stability.

Sb I wouldn't think you need to touch.

As I say this is going by DFI and a bit of research. Maybe figures worth considering.

RLM