Hi Robin, many thanks for your help. But I think the Problem is the USB 3.0 and I want to install Windows with a USB Stick. When I Mount the boot.wim and Import the usb Drivers i cant use the mouse and Keyboard in the setup longer. Is there anything else what I can do? Many thanks for your help

You followed the instructions here and prepared SATA drivers?

https://www.youtube.com/watch?v=lg8Oebhc3EI&list=PL1RkaknDn7v82tfEmxGgycwJJvJ0xGoqZ&index=2

Use these drivers to load at the screen where it says none are found:

http://www.dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=28J5R&fileId=3514149966&osCode=W764&productCode=optiplex-7040-desktop&languageCode=EN&categoryId=SA

You need to download and run to extract before use.

many thanks for your help.  I cant load drivers because no usb is detected. but i followed this instruction: www.dellindiatechsupport.com/83-2

This works for me.

Wow ... definitely the hard way.

Create folder on desktop, extract files and copy folder to the hard drive you are trying to install new instance of Windows. During error screen point to the file you copy on the hard drive