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.
I’ve found the source of the ticking, it’s a pipe bomb!
Yaaaay!