Ive been very motivated by this thread to save electricity. Here's my latest under volt setting..
Im running  7970,280x,7950,7870. All running in the mid 800 clocks and 900 memory.
.950mv across all gpu.
http://i.imgur.com/NmJHbKcl.png

Here's my total system pulling 666 watts.

http://i.imgur.com/WgWqqjEl.jpg