https://blog.wongcw.com/2018/11/21/%e7%9a%87%e9%91%bd%e5%8a%a0%e5%86%95%e8%8a%9d%e5%a5%87%e7%99%bc%e5%b8%83%e5%85%a8%e6%96%b0%e7%9a%87%e5%ae%b6%e6%88%9fddr4%e5%85%a7%e5%ad%98/