speedfan

I've recently put (my first!) custom loop into my system and have been seeing and hearing some strange things from my system fans. The way I am currently configured I have my pump connected to my mobo CPU fan header. The rest of my fans are connected to the fan hub that came with my case...

I'm buying a PCI slot blower to help direct some of my case airflow over the intakes of my GPU and exhaust some hot air. The fan I'm getting is two-wire, and connects via a molex. It's got a speed switch on the back which without looking, I'm betting just puts some voltage-drop resistors in...