It seems that Dragonborn cant handle ugrids set to 9 when i changed it back to 5 it ran absolutly fine no CTD at all. (7 was not tested by me)
To do that without loosing your savegame.
1. Start Skyrim and load your save. 2. Tab out and open your ´skyrim.ini (should be at "documents") 3. Find the line ugrids and set it down to 5 4. Back to the game and open the Console. 5. type "refreshini" 6. Save and enjoy Dragonborn.