Razer Tiamat 7.1 v2 Audio Problems

So I just bought a new PC and now I tried to setup my Tiamat 7.1 v2 again. I know that it worked on my old PC after some tweaks but I don't recall them exactly. My Problem: When I play the test sounds from Realtek Audio Console I can hear them nice and clear coming from the different channels. But when I actually play some music I only get sound from the front speakers. I tried that by playing with the volume of the different channels on the control unit. This is kind of my last hope. I hope someone can help me with this. Ps: I use the onboard sound card and not a dedicated one. But I read the manual of mine and it clearly says it supports 7.1