HOW did you get such a huge speed in Decred?! My 390 earns twice less! While doing the same speed as yours in ETH. What is the command line? What is the mem/cpu clocking?
I didn't change the clocks at all on these out of the box. AFterburner says core clock is ~1080, and memory clock is 1500 for each card. My config:
setx GPU_FORCE_64BIT_PTR 0
setx GPU_MAX_HEAP_SIZE 100
setx GPU_USE_SYNC_OBJECTS 1
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_SINGLE_ALLOC_PERCENT 100
EthDcrMiner64.exe -epool eth-us.dwarfpool.com:8008 -ewal wallet -epsw x -dpool stratum+tcp://dcr.suprnova.cc:2252 -dwal SantasNotReal.MiningRig -dpsw x -dcri 55 -dbg -1
PAUSE
I don't have a voltmeter yet (in the mail), so I just upped dcri until I noticed eth hash drop, then kept it. Much more dcri and I start to lose a bit of eth hash. I imagine the power/profitability is somewhere closer to dcri 45, but still need to do those tests.
Also, that screenshot was with dcri 65. 55 (current setting) gives me ~840 mh each card.
Edit: Great thinking with the "+" and "-" commands for dcri. Usability is something that is too often a low priority in the software world (I know, I'm an engineer myself)