Playing on a notebook with two monitors, one integrated (primary), another connected over hdmi (secondary).
The primary is hardconnected to the integrated Intel HD 4600, but is able to "stream" the signal from the GTX to the primary, which is used by all other games correctly.
The secondary monitor is connected to the more powerful GTX.
Now, if the game starts with the gtx the second monitor will be used. If I force DayZ to use the primary monitor (with adapter=0 or adapter=1) it can only use the weak integrated graphic card.