Right. So as you all know that I've switched out my RX480 for Vega64 because sod Nvidia right now. Daiyus mentioned about undervolting it and I have done with some surprising results.
First, I ran with just stock settings applied, GPU-Z reported 220W power draw
To begin with, I dropped the voltage straight down to 1V across the core and the HBM while leaving the clocks stock. Performance loss wasn't much, however the temperature did stay in the region of 60°C from 70°C when ran at stock. Also Power draw dropped to the region of 180W.
Now I decided to push the HBM, but drop the voltage even more. I dropped to 950mV across the board, pushed the HBM up to 950MHz from 945MHz and it did make a little boost on the performance, temps increased a tiny bit but the power draw stayed steady.
I did try to push the HBM to 1GHz but alas, I didn't win the silicon lottery this time and it artifacted like hell and then crashed the whole system, no matter what voltage I threw at it so I reverted back to 950MHz as a nice stable.
Now, the core. On stcok settings I was getting steady 1490MHz with absolutely no throttling. So I pushed up to 1510MHz and due to my HBM debacle, upped the voltage a little to 960mV giving a little performance boost, but at the cost of an extra 10°C and another 20W power totalling 200W
After, I dropped the voltage down back to 950mV, upped the core to 1520MHz and got a little boost with tiny little less heat and no power difference either.
So that's my undervolting experience so far. Leaving it there for now as it's stable and doesn't throttle under load, but I will return to see how many more volts I can drop before it ruins the performance.