OS re-installs don't always identify all your computer peripherals.  I would recomment removing your sound card from the motherboard and re-installing it.  Boot up as usual and notice if the computer identifies a new component.  Another alternative is to run your software to check for new hardware.  By aware, if new hardware is detected, you will need to provide drivers for functionality.  Do you have installation disks for all your hardware?  Your drivers will be located on the disks.  Otherwise, with hardware model in hand, try the manufacturer's sites for the latest drivers available. 

If the drivers have been discontinued, go to www.driverguide.com; they house drivers from all makes and models of every peripheral manufactured.  Free registration is required but you may find what you are looking for.