Headset problem

Hello

I have a Tecknet Headset which is working perfectly in Skype, but when i run Dota 2 game then there is alot of noise and rumble going on, when i call friend on Steam then the sound is perfect, once i run Dota 2 its terrible.

Any ideas what could be the reason?

Mobo: Asrock P67 Pro3

Thanx