I believe the power supply does have to be connected to the motherboard for the fan to come on... because the power supply itself won't work without a load. No power, no fan. But a bad fan can shut off the supply as well. The supply senses the current in the fan for stall or open. The ticking sound usually means the supply can't start. I'd suggest checking your drive cables to see if they're on backwards. Also check that all of the boards are seated correctly, and not offset in the slots which might short a supply.
