I bought a RX 480 reference (from gigabyte) 8gb 2 weeks ago and I was trying to undervolt it as much as I can.
Before the change, I had a hd 7970 with afterburner and I removed the drivers and the MSI program.
Using Wattman now, from 16.9.2 and now 16.10.1 drivers, I had on the state 7 1266MHz and 1025mv, which I thought it was great already (I'm attaching a screen).
That voltage is applied when I try 3D Mark or other benchmarks, but (for example) when I launch Gears of War 4 or other heavy games, GPU-Z tell me 1,15V. (tried also HWInfo)
It seems that Wattman settings are ignored.
I was able to undervolt with the new version of Afterburner, but I get some 100%fan bugs and BSOD (not due to the undervolt as they are happening even with standard voltage), so I hope I could do it from Wattman directly.
Someone can help me?