ECS 661GX-M2 V5 Manual page 21

Analog Audio Input Header
If you have installed a CD-ROM drive or DVD-ROM drive, you can connect
the drive audio cable to the onboard sound system.
1
CD1
When you first start up your system, the BIOS should automatically detect
your CD-ROM/DVD drive. If it doesn't, enter the Setup Utility and configure
the CD-ROM/DVD drive that you have installed. On the motherboard, locate
the 4-pin header CD1.
Chapter 2: Motherboard Installation
Pin Signal
1 CD IN L
2 GND
3 GND
4 CD IN R
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