You can change the fan speed in nvidia-settings but not below 35%. You need:
Option "coolbits" "5"
When "4" (Bit 2) is set in the "Coolbits" option value, the nvidia-settings Thermal Monitor page will allow configuration of GPU fan speed, on graphics boards with programmable fan capability.
so clock and fan is 5!
Then it will work. see:
I just can't enable the Power Mizer bit. What does your nvidia-settings for the power mizer tab look like?