Studio XPS 435MT, low sound after update

Studio XPS 435mt low sound after update.

The desktop is on window 7.

I downloaded and installed all available updates. Since then, the sound have gone off. I downloaded an updated latest drivers from REALTEC the sound came back after reboot. Later, I shut down the pc. When I turns on the pc, the sound is barely audible. I have uninstall  and re downloaded same and different  drivers but the Studio XPS 435mt low sound persisted. I have reset all that have to do with audio to the maximum none have effect.