I obtained a Compaq Presario 425. It has a 486 DX CPU and 20 RAM. I recieved it with Win 95 on it. Everything works except the sound. I upgraded to Win98 and still no sound. I have tried three sound cards that all work and no sound. After proper installation of each sound card the windows system reports that it is working properly and that there are no conflicts. I keep the volume control all the way up and the mute is not on. Nortons system checker finds no problems. Any suggestions??