I'm trying to connect the case front panel USB connectors to the motherboard. The USB plug from the front panel will fit on either the USB-56 or USB-78 motherboard connectors. Which one do I use?
The manual for the Asus P5KPL-CM says:
These connectors are for USB 2.0 ports. Connect the USB module cable to any of these connectors, then install the module to a slot opening at the back of the system chassis.
You can use either of the connectors. I usually connect the front panel connector to the one on the MB closest to the front panel in case I want to add another one on the rear.