Although AMD was quite clear regarding high bandwidth memory overclocking limitations, or the lack of any overclocking when it comes to HBM, back when Radeon R9 Fury series graphics cards were launched, it appears that Sapphire found a way around it and allowed both voltage control on the Fiji GPU-based graphics cards, including Radeon R9 Fury, R9 Fury X and the R9 Nano, as well as high bandwidth memory overclocking.
The new Sapphire TriXX 5.2.1 software comes with a new user interface which offers both voltage, frequency and temperature monitoring via neat looking analog dials as well as GPU voltage and frequency, HBM frequency overclocking and fan settings. According to Sapphire, the new TriXX 5.2.1 software also supports voltage control on other Radeon R9 300 series graphics cards.
It will be quite interesting to see how far would user be able to push high bandwidth memory as well as the GPU on Radeon R9 Fury series and the R9 Nano graphics cards with new voltage and frequency overclocking settings.
You can find the new Sapphire TriXX 5.2.1 software over at Sapphire's website.