How do I connect a product like this to my fans? That's where I'm stuck. I see 3 pins coming out for each fan but I have fans with 4-pin Molex connectors..
-snip-
See the plastic part below the pins?
That's what you should follow, your fans' connector should have a specific space where that part fits,
so even if the 4th pin isn't available, as long as the other three are in correct position, the fans will work.
The fourth pin (
control) is for speed control, the third (
sense) is for speed detection, but that device itself has a speed control switch so the fourth pin isn't necessary.
BTW, the comments about using a regular desktop fan works wonders.