I could solve the problem successfully
Slot 3 is only with x4 and not to change.....
I ordered a Hibryd Kit because the EVGA RTX 2080 Ti FTW3 Ultra Gaming is very thick and rebuild it and placed it on slot 4 and the first EVGA RTX 2080 Ti FTW3 Ultra Gaming on slot 3..
I placed the bridge...... and it works...sli modus is now on.....
..
I am more than happy.....
..have a look on the picture....
Many thanks to all of you for your super engagement and super support...!!!...
Peter