ECS geforce 6100 on board audio not working.

[astosoup]

I have a custom built with an ECS Geforce 6100 Board, AMD Athlon 64 bit X2 5600+ dual core CPU, 2gb ram etc. The problem is my on board sound recently stopped working suddenly. I have no sound what so ever through my sound card. And if i hook to the headphone jack i have some sound, but its nowhere as loud as with the on board. AND if i run call of duty 4 minimized it gets quieter and muffled sounding until i end it. Could this be my motherboard has STB or is it a driver problem? In Device manager it states my drivers are fine, and the device is working properly.