4 x 8 is not a validated configuration for the R12. That might be an issue. Only 2 x 16 is validated for 3200 or 3400 XMP.  
I recently bought two more ram sticks for my system. It seems that turning on XMP causes the system to infinitely reboot and giving me four yellow flashes (which I assume means ram error). The system runs fine with it disabled so I was wondering if there is a way to fix this so I don't just leave free performance on the board?
Aurora R12, ram error when enabling XMP with 4 ram sticks