My bitburners are running fine with
cgminer --avalon-options 115:32:10:35:380 --avalon-auto --queue 4 --bitburner-voltage 1285

I run them with 1170mV at 380 just fine.
Yes, but with the --avalon-auto they are running up to 455 ( BTB 0 = 453; BTB 1 = 455; BTB 2 =451 ) with this setting.
If the voltage is below 1285, they don´t reach the 450.