MSI BIOS Voltages explaned

Can someone with stronger understanding of matter explain each Voltage settings, because many users (including me) found it very confusive to handle with so many similar settings? My primary goal here is achieving stable undervolted CPU configuration, but I was unable to distinguish between following:

CPU VDD Voltage
CPU-NB VDD Voltage
CPU Voltage
CPU NB Voltage
DRAM Voltage
NB Voltage
HT Link Voltage
SB Voltage

For overclockers
In the computer enthusiast world the terms are not fully defined. The most used meanings are following:
VCore: The core supply voltage of an 'important' chip like your CPU or GPU, usually not the Northbridge. Most frequently used to indicate CPU voltage.
VDD: The supply voltage to your Northbridge chip or the supply voltage for the input buffers and core logic of your memory chips (mostly on graphic cards).
VDDQ: The supply voltage to the output buffers of a memory chip.
VTT: Tracking Termination Voltage. Compared to VREF to determine Hi/Lo
VMem: Supply voltage to a memory chip.
VDDR, VDimm: Supply voltage to the memory on your motherboard.
VRef: Reference voltage for the input lines of a chip that determines the voltage level at which the threshold between a logical 1 and a logical 0 occurs. Usually 1/2 VDDQ.
VGPU: The supply voltage to your graphic card's processor.

Hope this helps.

The only ones you need to worry about in that list are CPU Voltage, CPU_NB voltage and DRam voltage the rest are secondary and not likely you'll even need them.