Every chip has it's own voltage characteristics, you can't just copy someone else's settings. Trial and error is pretty much the only way to go. On the plus side, you really can't damage anything. If you drop the voltage too low you'll start getting graphical artifacts, driver crashes, etc. at which point you need to either bump the voltage back up a bit or decrease frequency. You should be able to use AB.
What temp is your GPU hitting that's making you concerned?