I have two profiles saved, one which needs just a little power-boost, and one with more power-boost (brings more heat). You will find a conclusion in the bottom of this answer.
First profile:
Core Voltage (mV): +6
Power Limit (%): +6
Core Clock (MHz): 1140
Memory Clock (MHz): 1550
Avg. framerate improvement*: +9 fps
Max temp. recorded: 75'C
Second profile:
Core Voltage (mV): +63
Power Limit (%): +40
Core Clock (MHz): 1160
Memory Clock (MHz): 1600
Avg. framerate improvement*: +10 fps
Max temp. recorded: 82'C
*The benchmark I did was in Gears of War 4.
My experience tells me that one can try to push both clock-speeds a small amout for each test not adding any more power. In the Gears of War 4 benchmark, I noticed that once the card needed more power, it would show weird squares randomly distributed on the screen. That was how I reached stable run of the second profile. However, I was not satisfied with the temperature of the GPU, but of course you can make your individual trade-off decisions.