[jaxx75]

I had 3 hard drives (likely) fail because of brownouts regularly occurring at a residence when high-amperage devices kicked on (power tools, air con, hairdryers, etc). The line would drop into the 80-90v range (120vac) which wasn't enough to turn anything off, but you could notice the lights "flicker." After a voltage conditioning UPS was added, haven't had a hdd failure

[jcrawfordor]

For situations where a UPS is too expensive or impractical you can also buy pure voltage regulators that use some kind of autotransformer, like the APC Line-R. I worked for an institution for a while that had every laser printer on one, there had been some bad experiences with losing laser printers to overvoltage incidents but they generally draw too much current to go on a UPS. I've also seen them used for A/V equipment.