Yes, they usually set higher starting voltage when on auto. That's because of stability and all CPUs not being equal in every aspect (silicone lottery), your particular CPU may work with much lower voltage for specified frequency. If you want set voltage than you need to set a particular OC. In that case voltage would stay on set level although the power (in Watts) will fluctuate with load. It is actually more critical value than Voltage, for heat and everything else. As Watts can't be measured directly, it's calculated from Volts and Amperes and Amperes are the ones that can do the damage to a component, not voltage itself. It's all just elementary physics W= A*V.