AMD E-350 + discrete graphics

Hi everyone,

I have a E-350 Build that unfortunatly isnt able to play any DTS-HD material over hdmi since fglrx doesnt support that (yet). Since I have a GT520 lying arround here, I thought I d give it a try. Now I added the GT520 to my system but it wont get recognized, the APU's HD6310 still outputs video but I cant get the GT520 work.

Anyone else with a e350 and discrete nvidia gpu who could help me out? thanks in advance