The sockets on one side of the UPS^* are battery backed up ones. The sockets on the other side are 'just' surge protected.

Why yes, I did have this PC plugged into the latter. The battery side had the old PC and the monitor.. and an empty socket.

Still it's been an excuse to have its monthly reboot into Windows for the various patches.

* 'Uninterruptable Power Supply', otherwise known as a battery which will keep mains-powered things running in the event of a power cut for a few minutes at least, long enough to turn them off properly or put them into hibernation until the power is back.

Edit: Ah, the cleaner managed to get water in the kettle's electrical contacts.