I have a GA-Z77X-UD5H I-7 series motherboard and processor and I tried connecting 2 ddr3 1600 rams. Surprisingly , although they are the same model,they don't work together. If I only plug in 1 the PC will work perfectly. Can someone explain why this happens? The PC is significantly slower when only using 1 ram (4 Gbs). I forgot to mention that the same Rams were used in a msi motherboard that stopped working for an unexplainable reason. Should I downclock one of the Rams to 1333 from 1600 ? Won't this set my motherboard at risk though?