https://blog.wongcw.com/2021/12/22/%e7%be%8e%e5%85%89%e7%a2%ba%e8%aa%8d%e5%9b%a0pmic%e5%92%8cvrm%e7%9f%ad%e7%bc%ba%e5%b0%8e%e8%87%b4ddr5%e6%a8%a1%e7%b5%84%e7%bc%ba%e8%b2%a8/