My equipment was not happy with a consistent 123-125V I was getting for years, transformers humming, can't be good for transformers. I finally built bucking transformer to be rid of the constant humming.
I did suffer both microwave oven and furnace motor failures during this period of high voltage. Since utility finally came in and fixed over voltage issue, no failures, no humming. I monitor my voltage 24/7, now between 119-121V, exactly 120V at least 90% of time.