CPU Vcore not throttling down when using custom voltage(GA x58UD5)

Hi guys. When i leave the vcore voltage at default, CPUZ shows me that the vcore throttles down to .987v at idle. but when i manually set the vcore to 1.200v, the voltage does not fluctuate, it always stays at 1.200(idle or load).

according to gigabyte mothetboard application, the cpu is consuming around 6-10W at idle when the voltage is at 0.987 but it stays around 16-20 when the voltage is frozen at 1.200 at idle.

Is this normal, or is there a bios setting that allows the voltage to throttle down even when using custom voltage settings.

Im running 200x19 at 1.200v and 185x20 at default(0.987 - 1.165). both are stable with aircooling after 30mins rendering session. I want to run 200x19 so i can max out my ram but it is not stable at default voltage.

yes, but i dont think i can get it down to 0.975 which is the throttled vcore at idle when in default.......

it would be nice to have a fluctuating vcore for for idle and load.

the wattage/temp difference between 1.187 and 1.200 is minimal, so there isn't much point.