Posted 04 May 2006 - 10:11 AM
Your top one is so that you can listen to a music CD and do other things on your computer while not having music cranked so loud that it wakes the neighbors. It's sort of like a portable Cd player (the old "Walkman" if you will). This jack (port) will only work when listening to a CD. If you play music from your hdd, or off the internet, you won't be able to hear it when using this jack.
The one on the bottom is for having a "curtosey" port in the front so that you don't have to continually move your computer to plug a headset into the back. This one you should be able to hear everything through, whether it's off a CD, your hdd, the internet, or a game. This port is controlled by the computer, so it will put all sounds that the computer makes through this port. Of course, the port itself doesn't have a volume control, as the sound is coming from the motherboard (unless you have a sound card, then it comes from the sound card), so the computer has to control the sound (meaning that whatever program you're using has to control the volume).
Basically, the socket on the tower plays all music and sounds that you can hear that your computer makes.
The socket on the CD drive only plays sound directly from the CD player itself (only when you have a CD in it).
Hope this helps!
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