Keeping tradition with doing things backwards, I’ve finally got a UPS for the rack (mounted in the bottom of the stack). Got a PowerWalker VI 2200R. Its a 2U unit which is all the space I’ve got left in the rack. Decent price and decent I/O with USB, serial and a slot-in for network expansion + 4 IEC outputs. Its powering everything in the rack and connected via USB to my main server which runs a NUT server that other machines can connect to. A calibration run (100-80%) puts the runtime at about 20 min. Long enough that I’m comfortable setting things to shut down when 20% capacity remains. Summary, I sleep better now.
Brownouts are a thing, and can kill devices just as well as anything else. And th can be undetectable by human senses. They won’t necessarily cause even a microwave to lose it’s clock.
Unless you have a measuring device at your location, you really have no idea what your power looks like.