The signal from your DVD player, when it is playing a DVD, goes directly through the motherboard to the sound card. (This is good) The sound stays in the digital format until the sound card gets ahold of it, then converts it into an analog signal for the speakers. When a CD is put into the DVD player, the signal is sent to the sound card via wire. There usually 2 connections on the back of a DVD player. One is a digital CD out; the other is an analog out. If it is the analog signal then the DVD player is putting out too strong of a signal to the sound card. (A digital signal can't be too loud) My guess as to the solution your volume problem; pull off the case and see which is connected. The digital wire uses 2-wires, the analog uses 3 sometimes 4. Look at your sound card instruction manual and find the CD-IN port on the card (internal) and hook it up. You can then go into sound properties and add the CD Digital to your volume controls and adjust it however you want. Since the CD player will be the only input on that line, the volumes of other sounds will not be effected.