Help with 5.1 system

[Alessio88]

Hello everybody guys,i have a strange problem on my gp4,i had to format the pc because i've change the motherboard,now that my gp4 is back on duty,i've just noticed that in game and in menu of my 5.1 system only works the central speaker and the suboower,but when i'm in windows all 5 speaker works well and the suboower as well.
I tried to re-install the Realtek drivers but nothing change,can someone help me please?thanks in advance

Greetings
Alessio