my question: is it safe to just go lower and lower with the voltage (to keep the fanspeed lower), or can that physically damage the card?
Yes it is completely safe, you know it wants more voltage when you start seeing artifacts/ miner hangs/ rig reboots. Just add some voltage or lower clocks even more to find your sweet spot.
Also try ubq, exp and music with 7990.
thanks, greatly appreciated!
lowered it to 950 with the result of "AMD driver crashed", increased to 975, seems to work, will monitor it over the next 24hrs
its far better now, 65°C with 70% fan
indeed eth coins with a smaller dag are great as the speed on the 7970 cards is fine there but its by far harder to setup autoswitching with that (and im using nicehash where this isnt possible as well)
when i got some time i might look into the real numbers in terms of profitability and if they differ by far from my current rates i might setup "manual" mining or mining via mph or the like
