I can get my 8350 w/16GB DDR3-1600, 990FX, 1 SSD, 7950, and 7 fans to idle around 65W at the wall at 4GHz. CnQ enabled, C1E enabled, and just manually undervolt. Undervolting doesn't do much for idle (but does for loads) - idle is more about the total platform consumption.
Either CnQ or C1E will have a large effect on idle voltage, enabling both will help a little more but not much. I've never had issue with CnQ and overclocking (beyond a 18.5x multi limit on Thuban/Phenom 2 for CnQ to work).
FYI, AMD dual monitor adds about 30W to idle when I last tested it on my 7950 (290/x may be different), since the GPU VRAM need to run at higher clocks. My 780 doesn't do this and the GPU runs at the lowest clocks with dual monitors.