Dell drivers optiplex 990
i can download the software of that computer
You download the drivers from the Dell Website
You should download "Dell Installation Manager" First. This makes the automatic installation of other drivers easier...
If there are no drivers in the computer to access internet, you can use another computer, and save the drivers to a thumb drive, etc...then use the drive to load the drivers into your computer.
You should shut off the firewall and antivirus while installing the drivers. Then restart and turn the security back on.