I ended up buying a mixture of 390 cards a while back, only to realize it seems none of them support undervolting (Tried MSI Afterburner and Trixx)
I have an old R9 290X Reference card back when Litecoin mining was hot on them. It can undervolt -100 and works amazing, in this heat it's as good as my 390.
What cards do you use that you can undervolt? Is there a custom bios for the 390s that allow this? I'm also interested in the 400 series, seems they all can be undervolted?
i undervolted my R 9 380 its efficient,low power consumption