I have an RX Vega64 Liquid Edition and I've been trying to undervolt it, even by a little, ever since it came out but for some reason the display drivers always crash after playing any game for a short period (around 30 minutes of playtime before it crashes). The very first undervolt I tried was when I first got the card and I used the Tomb Rider benchmark as a "stress test" to see how low I can push the P7 and P6 voltage. I was able to get it as low as 1050mV P6 and 1135mV P7 without crashing in the benchmark. I also overclocked the memory to 1100 and left the memory voltage at 950mV. But after I would start playing, the game would crash, followed by a display driver crash and this has been the norm since the first display drivers to come out for RX Vega all the way until my current version of 17.12.1. I've noticed that the Radeon Adrenalin update bumped my P7 default voltage from 1200mV to 1250mV and now if I lower it back to 1200mV it just crashes again. Same story, I was playing Mad Max for a while and it would just crash.
Could someone please help me out with this? The power usage, as everybody is aware of, is crazy high on Vega64, often over 350W. The only way to get it down is by either using Chill or by undervolting. I'm not a big fan of Chill because it also means lowering my fps and I got too used to playing games around 120 to 144 fps to the point where the game looks like it lags if it falls below 80fps. When I first undervolted using the Tomb Raider benchmark, I was able to get the power usage down from 360W to about 250W and manage to keep the same performance while also running the GPU cooler. But I knew it was too good to be true and the following crash during gameplay proved me right.
you need to drop the max core clock a fraction, as the LC version boosts a fraction higher than the others, hence the extra 50mV.