Very noob question. I'm doing my first build and I tried to pick up six Coolermaster fans today for $10. But when I saw the fans I realized that the holes for the screws did not have threads ... how do you install them if theres no threads? do I have to buy a separate nut or something??? I didn't get them b/c of that plus all the fans had 3 pin connectors, which would have forced me to buy adaptors for them too. Help??