RAM Change to DDR4 3200 2x8GB

Hi, iwant to change the RAM from the installed BIWIN16GB 2666 to 2x8 GB DDR4 3200 Ripjaws from G.Skill. So I installed both and the RZBOX did not start. If I install only one (8GB) there ist no problem and the RZBOX starts, of course only witz 8GB. I tried to use the 16GB BIWIN in the second ram-slot, first slot unused, RZBOX did not start. Maybe the second memory-slot ist not workeing. Do I have to make changes in the Bios to use the second slot?