If I am not mistaken, the VRMs on that board are pretty decent. Should be ok for an 8-core chip plus overclock. How much an overclock I couldn't tell you. Regardless you will need good airflow.
Looking for one of these cheap. Prefer original box and cooler but not a deal breaker depending on your asking price. Will consider an 8-core chip if its a sweet enough deal. Shipping is to 27127. Thanks!
My heatware
FOUND
I have seen Vega 56 cards go for under $200, but only if you like tweaking with the voltages and power tables (and can deal with the power draw). It will provide a nice performance bump over the 1070. Gamer's Nexus and Hardware Unboxed have a couple of comparative videos.