An optical audio cable should have a red light at each of the connectors when it's in place and working correctly. There can be many cases when the optical cables cease to work. With the new setup the light will be off unless there is an active audio file, video, or other sound playing on the PC. Here are some common signs that may indicate your optical cable is not working properly: No signal or poor signal quality: If you're experiencing dropped. This guide breaks down the invisible barriers in the digital audio chain, from the physical connection to the complex language of bitstreams, ensuring you can finally get your system to sing. Follow these steps to ensure proper setup: 1. I spent hours and hours trying to find out why it won't work, checking my bios, removing and re-installing drivers and searching the web.