I want to run my GPUs with only 80% of their original power draw. Should I rather setup -powlim or -cvddc and - mvddc?
-powlim set power limit, from -50 to 50. If not specified, miner will not change power limit. You can also specify values for every card, for example "-powlim 20,-20,0,10".
Note: for NVIDIA cards this option is not supported.
-cvddc set target GPU core voltage, multiplied by 1000. For example, "-cvddc 1050" means 1.05V. You can also specify values for every card, for example "-cvddc 900,950,1000,970". Supports latest AMD 4xx cards only in Windows.
Note: for NVIDIA cards this option is not supported.
-mvddc set target GPU memory voltage, multiplied by 1000. For example, "-mvddc 1050" means 1.05V. You can also specify values for every card, for example "-mvddc 900,950,1000,970". Supports latest AMD 4xx cards only in Windows.
Note: for NVIDIA cards this option is not supported.
What's the difference between target GPU core voltage and memory voltage? I didn't do any voltage settings so far, I only worked with power limit in MSI afterburner so far
They are pretty self explanatory terms, GPU core voltage is for the actual GPU processor itself (the chip) and memory voltage is for the actual memory chips on-board the GPU.
Most of the time these will be set the same values as each other, but for advanced tweaking they can be set to different values with the one caveat that the memory voltage cannot be lower than the core voltage.
To adjust the power level with AMD cards, it is recommend to adjust the voltages. You can probably start safely with 950 for both the core and memory (which represents 950 mv or 0.095 V) and work slowly down from there until your GPUs hang or crash. Then add back another 20 mv and you should be close to the sweet spot as far as energy saving versus power consumption. For example say you make it down to 850 mv before the cards hang, then you would bump your settings to 870 mv and run that for awhile to test for stability. It basically will take some trial and error as each system and graphic card will be different as to how much undervolting it will tolerate.