Ever since I hooked my printer up to the Ethernet (over a patch panel), it makes a ticking sound exactly every three seconds.
Before, it was connected via Ethernet cable to a Raspberry Pi that served as WiFi adapter, and that setup didn’t tick.
Update: The ticking stopped after deactivating DHCP. It’s a Kyocera Ecosys M5526cdn.
It’s counting down the time until the enforcers arrive. They’ll rough you up for not buying enough ink. If you complain they’ll point to a clause in the EULA that you agreed to.