Implementing voltage control on Fiji was more difficult than on most other cards. While the voltage controller on these cards is well-known and supports I2C (a method to talk to the voltage chip from the host PC through software), getting I2C to work on Fiji in the first place posed another set of challenges. Unlike NVIDIA, AMD does not provide good API support to developers, their ADL library outdated and buggy, with updates spaced years apart. So most software utility developers implement hardware access in the hardware itself to write directly to the GPU registers AMD is changing with every new GPU. AMD's developer support is pretty much non-existent these days. All my contact has been worried about for four weeks now is that I make sure I use AMD's "new" GPU codenames in GPU-Z (for the R9 300 Series re-brands).
