for less power you could undervolt the core to may be 900.
for even less power, core speed to 1075-1100 and undervolt to 850-875 but then the hashrate would drop also. you have to experiment to see which sweet spot you like.

Mine now are kept at core 1100/880 mv   mem 2000/1000mv - around 29 mh for eth.  aprox 110 watt from the wall. I can get to 31 mh, but don`t like the electricity usage at that level.