The Dell Optiplex 755 computer you can download the SoundMax HD driver below for this hardware. This is the audio driver which you can install on your computer. This is version 7 of the SoundMax driver. You will need to download the driver and then open the zip file. Inside will be the install file which you simply need to click in order for the install to begin. It is an easy process to install this driver file.
Dell Optiplex 755 : SoundMAX HD Driver
This is the Analog Devices ADI 198x Integrated HD Audio Driver which works on the OptiPlex 320, OptiPlex 330, OptiPlex 745, OptiPlex 745c and also the OptiPlex 755. There is also the Precision T3400 as well as the T5400 and finally the T7400 computer range from Dell. When you click on the file inside the zip file it will extract all the drivers onto your main drive being your C:\ drive into a directory it will create called the Dell directory. From there you simple need to click on the install and it will install the SoundMax driver onto your computer.
The driver will work on the Windows 2000, Windows XP as well as the Windows XP x64 operating system.