U are right, the Sound is the Problem.
I tryed Arma's Link, it works without sound.
But i dont know what i can change - in my opinion the Sound is set to stereo...
As I used the PC at home (with my Wireless Headset, Steelseries Arctic 9, connected by USB) there was no Problem - now i dont use a Headset, only Monitorspeakers, connected via HDMI, it doesnt works.
I also tryed in Device Manager:
- disable Realtek Sound
- disable NVIDIA Sound
doesnt changed anything.
Then I downloaded the newest Sounddriver from Mainboardpage - nothing changed -.-