I have a Phanteks Eclipse P400S Tempered Glass and i find it impossible to plug in the hd audio into my motherboard. It only goes half way into the header. If i push too much i'm afraid i will damage the board. There isn't any dust or any stuff stuck into the hd audio, because everything is brand new, so that can't be the reason. Also i've found some other posts similar to mine without a decent solution, other then pushing it in with all the force you got...