IMHO the voltage settings make no difference with the S3+ ( change on GUI without modifying config files )
I have tried alot from 0500 (which is too low für the asic to run) up to 0800. On my tests it make no difference on GH/s or power-consumption or HW-Err.
Only setting of Frequency makes a differnce.
Freq Volt Watt Temp A B Fan GH/s HW W/GH
225 0,77 380 38 36 1600 449 0 0,846325167
250 0,77 440 39 36 1800 505 0 0,871287129
250 0,72 440 39 36 1800 505 0 0,871287129
200 0,72 330 37 25 1500 408 0 0,808823529
100 0,72 161 36 35 1000 210 0 0,766666667
100 0,50 161 34 33 1000 208 0 0,774038462
Always with power off/on and running for 1 hr.