I was in a hurry, so no time for a detailed answer
I'm running the already undervolted AVS-kernel (not the CAVS one). I'm able to undervolt my nexus by 50 mV awake, and even 125 mV at sleep (both, min and max). So I'm running at 900 mV awake, 825 mV asleep on lowest clock.
But be warned, undervolting mostly makes your device unstable, by a very little amount of saved energy.
I also made this fault and blamed iR for my noobish behavior (see some posts back. BIG apologize to the greatest kernel developer ever
)