got a question bout "CPU NB Vlotage Control", it's kinda hard to search cause "NB" isn't searchable

anyways the warning txt for "CPU VID Control" says CPU NB voltage has to be equal for phenoms. i'm just confused cause there is also "NB Core Voltage" and "NB HT Voltage", what does "CPU NB voltage" control anyways? i followed the warning message advice and i managed to hit 3.0ghz though.