ASUS P5GD2 "Line In" Audio Problems

[infini]

I have set up a PC with Asus P5GD2 with Windows XP SP2. After installing audio drivers (CMI9880 high definition audio), i went to control panel ->sounds and audio devices-> volume(under the sound playback tab) and i couldn't find the "line in" option. I also looked in the properties of volume control but there was no "line in" . I have set up several Asus 5PGD2 motherboards and i always experience the same problem. I have a pci tv tuner card and i can't use it beacuse it needs to connect the line out of the tuner, to the line in of the sound card in order to have sound.