When the PC is turned on, the SPEAKER “+” signal outputs +5V, this is how ES03-WIFI determines if your PC is on or not. So we recommend that you choose a motherboard with standard PC speaker header. If you have no other choice and is technically inclined, you may connect to other signal output pins on the motherboard that are between +3.3V ~ +5V when PC is turned on, and no signal voltage output from the signal pin when the PC is turned off.
If the signal pin header is different from the included SPEAKER cable, only insert the signal pin. (+5V, GND pin is empty)