"AC97" is not a model number nor a sound chip number, it's a term invented in 1997 by Intel defining sound standards. Almost all sound chips built between 1997 and 2007 were "AC97" compliant. It was replaced by High Definition types.
A good start would be to identify the computer/motherboard brand and model as well as a valid sound chip number and type. Then say if it's for a laptop or desktop computer.