I tried changing both power stage and undervolt while measuring the power consumption, it is strange I didn't notice any change, not even 10w.
The measurement was taken directly on the wall, no software involved.

Anyone else experienced this ? Is undervolting really works ?

Running latest image of SMOS.
My cards are XFX RX580 GTX 4GB, XFX RX470 8GB ( red fans ), Sapphire RX470 Nitro+.