I’m not sure anything makes me think “old computer” as fast as the possibility of bent pins in a connector:
If the USB ports of an Apple display with an Apple Display Connector (ADC) won’t work, a pin or pins on the connector may be bent.
When you turn on the computer you hear the startup sound and the picture on the display appears, but the USB ports on the display don’t work.
Here’s a link to the Wikipedia entry for the Apple Display Connector, first shown off in 2000. Data, power and video all over one cable, just like we have today.