For Ubuntu 16.04 LTS
The card pulls 112Watt at the wall..maybe even less.
at 900 mhz gpu, 800 mvolt
1750mhz ram, 1000 mvolt
I was able to do 1200mhz gpu, 850 mvolt
1750mhz ram, 1000mvolt
It seems that the card becomes very power inefficient once it passes around 1100mhz-1200mhz gpu core.
I am going to test what I can undervolt the ram to and lower core gpu mhz as well.
How to reduce the memory frequency in UBUNTU?
The "PolarisBiosEditor" like there is no way to change the memory frequency.