The Dell driver is required, non Dell drivers will either not work or not work correctly.
First thing, is the Integrated Audio enabled in the BIOS? (F2 at boot up to enter Setup).
Second, on Dell's (and many others) if the motherboard chipset drivers were not installed, the sound device will not work. In this model there are Intel motherboard chipset drivers. Try installing them and then the Dell sound driver. Dell Drivers