Power supply question

Guys I have an extra 250 watt power supply I want to use as a "tester".

I haven't tried this yet, but I want to test out some case fans.. Can I plug in the power supply, and then the fans? will they work, or do I need to jumper a couple of pins on the main mother board hook up? or put a switch in there, like there would be if the Power supply was hooked to a mother board?

Thanks..