how exactly did you lower vcore to 662mV?
From RedTeamMiner documentation:
To be able to lower voltage properly, you need to modify the powerplay table
with e.g. MorePowerTool. Install GPU-Z and MorePowerTool. Save the bios using
GPU-Z. Open MorePowerTool, select your Big Navi gpu in the dropdown list. If
necessary, load the bios to get a baseline configuration. Lower the "Power
and Voltage" -> "Minimum Voltage GFX (mV)" limit to the voltage you with to
run. Lower than 625mV is rarely stable, although we've been able to run at 612mV.
Then you Save, Restart Windows and you will see the new minimal core mV to the number you choosed.
hmm, ok, but power slider in Radeon Software dont work as I want. I did try to set Minimum Voltage GFX to 625mV and it was around there, but I could not raise it to 700mV with that slider in software.
Power limit is also buged. If I go over 15, max freq drop to 500Mhz.