Until now, you've had to use AMD's own Radeon Software and its pretty damn impressive Wattman overclocking utility, or SAPPHIRE TRIXX, and lastly ASUS' GPU Tweak in order to overclock Vega. We can now add MSI to that list.
MSI's latest Afterburner 4.4.0 Beta 19 has support for low-level access to the SMC microcontroller, providing full voltage control over Vega. This means you can adjust the voltage on Vega up and down, if you want to get into some undervolting action, too. You can't make any per P-state control adjustments, with a slider provided instead.
MSI states in its own changelog: "Added low-level AMD Vega 10 graphics processors family support. This means that now MSI AB can access this GPU directly without AMD ADL API, so more powerful voltage control (no longer limited by AMD ADL API) and extended and more efficient low-level hardware monitoring are available for Vega now. Core voltage control for reference design AMD Vega series cards is now performed via low-level access to on-die SMC microcontroller. Voltage is adjusted in offset form now, applied to all P-states (just like it was on Fiji/Polaris) and full -100..+100 range is available. Added GPU power draw graph to hardware monitoring module for AMD Vega series graphics cards. Added HBM memory temperature graph to hardware monitoring module for AMD Vega series graphics cards".
Surprise! MSI includes a tease of the GeForce GTX 1070 Ti in its own Afterburner changelog, with support for core voltage for the reference GTX 1070 Ti. The changelog said: "Added core voltage control for reference design NVIDIA GeForce GT 1070 Ti series graphics cards".