I don't have it either with my Fury X, I guess it's a RX480 feature only but why did they say they renamed overdrive when on my 16.6.2 it's still called overdrive.
That might have been a reviewer that said it so they might have just gotten it wrong.
The "Wattman" thing is a RX 480 exclusive feature.
AMD said elsewhere (I think on reddit?) that they will "think about" making it work on older cards.