I'm trying to plug the rainbow of wires into my mobo, but I'm having problems identifying the correct pins. I have this gray block thing, I guess to make plugging all my pins in easier. It has 2 pins labelled "HDD LED+" and "HDD LED-". Simple enough. I look at the cable coming out of my case...there's a 2pin HDD LED cable. Perfect. Except it's not labelled "+/-". One pin is labelled "G", and the other has a triangle with a "s". What the heck? Arrrrrgh. Does "G" go into the negative or the positive?
The drive LED cable is probably white and some other color, yes? The white wire goes to the "-" terminal on the motherboard. But Ghislain is right. If the LED does not illuminate, reverse the connections.
All diodes pass current in one direction. You pass current through an LED and it illuminates. If it is hooked up backwards, no current flows through it. No current through it means no load on the motherboard.