[CentOS] Black screen after boot on CentOS 7.2

Mon May 16 10:53:04 UTC 2016
Oliver Zemann <olze at trustserv.de>

Hi, i just installed CentOS 7.2 on my little "server" but i get a black 
screen during boot. It is a Asrock Am1h-itx mainboard with an AMD 5350 
CPU (onboard graphic).
I created a raid 6 but i dont think thats the problem, as the boot 
process goes pretty far. I would even say its going until X should 
start, but it is a server install, so i guess there is no X.
Can someone tell me what could i do to get more information? Is there 
some kind of nomodeset param available for the grub cmd line param which 
i could try?