Soundcard plugin

hi bitches,

just one question. So i have this motherboard with onboard soundcard (http://www.gigabyte.com/products/product-page.aspx?pid=3006#ov) and i have Razer Kraken pro headphones. My question is in which plugin should my headphones be plugged in to get the best sound/ or to get all sound from the game. (happened to me in gta that i only got like hald of the sound from the game,(didnt heard car driving and talking etc.))

Thanks in advance.