You may want to back up a bit. If all you have is RAM, just sell it and get DDR4. If you actually have a current system, you may want to start by listing the specs. Many platforms use DDR3 RAM, you can't just ask for a CPU in the same speed range because it may not fit your motherboard. And if you are going to swap the motherboard, you may as well spend the extra $40 on new RAM and new platform.