The 9020 sff mobo Front Panel 9 pin header is standard usb 2.0 9 pin.

you see 9020 sff front panel has 2x usb 3.0 ports (#8), 2x usb 2.0 ports (#9), audio.  The two usb 2.0 ports have a standard cable to go to the 9 pin header. You just have to connect new case usb 2.0 cable to it after swapping case.  If your case is new that it does not have usb 2.0 ports at front, use a Dell oem front panel part. It can be from any old Dell desktop such as old Vostro 200.  It is a generic front panel part that usually has two usb 2.0 ports that are combined to one cable to a 9 pin usb connector to be installed on mobo header.  The single 9 pin header can be thought as dual usb channel as it supplies two separate digital signal to two usb 2.0 ports up front.

How about USB 3.0 pin? is that compatible with standard USB 3.0 connector?

You have to buy a jumper or use wire wrap to jumper pins 7 and 8 together. Or bridge the pins together with solder on the underside.

Yes it is.

https://dl.dell.com/topicspdf/optiplex-9020-desktop_owners-manual_en-us.pdf

Hello, neither of the USB connectors give the error, its just the 12 pin Audio connector that gives the error.
I tried chasing the pinout but I guess I'm not smart enough.
my solution was to take the front IO panel apart and remove the audio cable and place that into the new case.
hopefully this helps someone.

Buenas brot, me podrias ayudar con el diagrama para el switch de power? Quiero cambiar el cabinet