Can someone explain QPI voltage and DRAM voltage under these circumstances:

I have 12GB of Corsair DDR3-1600 CAS8. Label says 1.65v

If I set the DRAM frequency to DDR3-1333 and everything else on AUTO, I get the following measurements using TurboV:

QPI/DRAM Core Volt = 1.20000v
DRAM Bus Voltage = 1.66v

If I manually set the DRAM bus voltage to 1.5v it reports 1.5v

If I want to run the RAM at DDR3-1600, I set the frequency to DDR3-1600 and leave everything else on AUTO, I get the following from TurboV:

QPI/DRAM Core Volt = 1.37500v
DRAM Bus Voltage = 1.66v

I can manually set the DRAM to 1.64v and it will report 1.64v but if I try to lower the QPI/DRAM Core Voltage to 1.2v, it fails to boot.

I am worried that the mobo is over-volting the QPI/DRAM Core Volt setting. What are 'safe' voltages if i want to run it at DDR3-1600? Can anyone recommend safe settings?

Thank you