Polarity of HDD-LED and PWR-LED on Mainboard

I have a Supermicro Mainboard and want to connect the HDD and PWR LEDs of the chassis to it.

The chassis gives the following cables:

1. HDD LED (2 wires, one is marked with "+", one with "-")
2. PWR LED + (1 wire)
3. PWR LED - (1 wire)

I now want to determine where I have to plug in 2. and 3. and the direction of 1.

The mainboard manual says:

Power LED -- Pin Defnitions (JF1) Pin# Defnition 15 3.3V 16 PWR LED HDD LED -- Pin Defnitions (JF1) Pin# Defnition 13 3.3V Standby 14 HD LED 

So I know the pins, but not the polarity -- what is meant by the "3.3V [Standby]" and "xy LED", which one is plus and which is minus?

1 Answer

Mainboard LEDs are typically switched on ground and the description of JF1 confirms this:

• "3.3V" is positive (+)
• PWR LED resp. HD LED is negative (-)