I have the same case and I also have a "leftover" connector with LED written on it. On the front panel where the "interface" (buttons, jacks and leds) is, there are three LEDs ; a power led and a HDD led, and I have no idea what the led in the middle is for. I believe that's what the connector is for ; I haven't found a spot for it on my mobo. Maybe reading the case manual would give some insight as to what the LED is for... (I didn't get to that part of the manual)