Right. This is why I never buy fans with only a 4-pin Molex connector Basically, a normal 3-pin fan connector has 3 wires connected: 12v, GND and RPM. A normal fan controller has a variable resistor that connects to the 12v line of your fan. The knob can be used to turn fan speed down. Your ZM-MFC2 (wild guess ) works a little different, but you should still be able to control any properly connected fan (with 3 pins!) with it. 2 options: - Mod your 12v and GND into the same connector your RPM sensor is on (which is wired Yellow (RPM), Red (12v), Black (GND) - Get fans with a normal 3-pin connector. EDIT: I just saw your adapter cable. Mod the RPM wire into the empty hole on the small connector there, should work fine.