As far as overvoltage from the POCO goes, about 15 years ago the entire town here had about 132/264V on one of the 3 phases. Took the POCO about a month to straighten it out. Seems the loads on the 3 phases was out of balance over the entire town.
Another time, when the big blackout in the Northeast in August a few years ago, I didn't lose power, but the line voltage oscillated from 90V to 140V every half minute for about an hour. I turned off all the air conditioners, fridge, freezer and the dehumidifier when that happened. The PC didn't mind it for several minutes and then I unplugged it as I didn't want to push my luck...
