has more to do with your psu than the (edit for INPUT voltage I mean) voltage you are running at.. pretty much 240v to psu vs 120v to psu comes down to how many amps the psu draws (how hot is the psu and the cord to wall going to get) psu to machine is 12v and whatever amps the settings draw, it doesn't give a flip at that point what the input voltage is. (240v is better for many reasons, but primarily (for miners) to ease the workload on your psu, and in the case of certain dual voltage psu's allow for more watts to be drawn (which also decreases the work load on your psu.) over half the problems I've encountered with people overclocking was about the psu and not so much the machines. - The other half was about improper cooling. (Either from manf end. or user derping)

All that being said lowering settings is still probably the right choice.