light blue cable on pc mother boards?

Question

what is the light blue audio in (line in) whats is this used for

Answer 1

If you want to record off a radio, or an external device like a record player, you just need to have a patch cord, running from the external device to the line-in port. You can record it, or listen on your computers speakers. I do that with a turntable, even if it has no amplifier hooked up to it, your computer can act as an amplifier.
If you have a cassette player, you can record the songs on the computer, and make MP3's from them.