gillem welcome to the forum. Please read the rules. The posting are to be in English. Your photo story would be much more informative if you translated the German text to English. You could use the Google German to English translator (copy and paste edit your post).
For example your second paragraph translates to:
"The aim of the conversion is from the outside as little as possible on the housing or more
told to change nothing at all . Be front connectors and back connectors standard
such as original in the housing are used . Inside is just the drive cage
offset for an ATX motherboard . All partitions remain in the body and are only
adjusted so the get the air tunnel remains ( Plexi - side wall , G5 CPU - sheet ,
original fan 's changed for ATX board ) . Power supply is " gutted " and a normal
600Watt ATX power supply packed into the G5 PSU housing .
Place behind the PCIe I have enough to keep clear because besides the long graphics card
also an equally long PCIe " sound card " into the system comes ( an Avid HDx 16x16 ) .
If I will get along with the 4 USB ports ( 're original then one front and three
back) I have to look else has one IEEE1394 port for another USB
soft . For it can only keyboard and mouse to a USB hub , the external
Audio interfaces need also come off of the bandwidth depending ago
its own USB port (external is still an Avid Eleven Rack , Line6 POD
Pro XT and a Steinberg UR22 via USB to the system ) ."
Good modding,
neil