Nvidia 754 - Manual (Page 63)

Driver Installation
Page 6-3
Equalizer:
Speaker
Configuration:
3. There are 10 bands of equalizer control, check "ON" when you want to adjust
the equalizer.
4. This page displays the mainboards's phone jack function when a corresponding
audio mode (no. of speaker) is selected.
Figure 4 above shows the phone jack setup for 2 channel mode.