In addition I compared with my mothers D34010WYKH which immediately drops processor frequency to 0,7 ghz when no CPU load occurs.
OK I solved it. Somehow the Windows Power Options was the cause. A couple of days ago I made a power plan through Samsung's Magician (their own SSD software) and changing back to "Balanced" solved my issue. The weird thing is that if I go into the advanced settings for the Samsung SSD Performance plan it is exactly the same as what I have in the advanced settings for "Balanced" e.g. "Minimum processor state" at 1%.