Here I talk about how to understand the memory parameter.
My system CPU is Celeron J1900 , memory is Kingston CBD16D3LS1KBG/4G,4GB,DDR3-1600,SODIMM.When I use the CPU-Z to detect their information, it will display the below content.
At the capture 1, CPU-Z detect the CPU type as Celeron J1900 ,and its Core Speed 1999.10MHz,L2 Cache 2 MB .All of them match its specification that can be found in the intel official website.
At the capture 2, DDR3 & 8GB are correct info about the memory. We noted DRAM Frequency is 666.7MHz, it seems not match the memory frequency 1600MHz .However, we need to know what DRAM Frequency is.
Double Data Rate(DDR) technology read/write the data following the Rise time and Fall time(脉冲的上升沿和下降沿). It means memory read/write data two times during one time clock cycle.
DRAM Frequency is the real time frequency, so memory real frequency equals to Double DRAM Frequency .
So, DRAM Frequency is 666.7MHz,the real read/write frequency is 1333MHz. it also seems not match the memory MAX frequency 1600MHz.What is the root cause for this? We found the answer from the CPU J1900 specification.
CPU J1900 only support the MAX memory frequency 1333 MHz , no matter the physical memory frequency is 1600MHz or 1866MHz,the MAX real frequency just can reach 1333MHz.
At the capture3 ,SPD is the physical memory info generated by the manufacture vender. [MAX Bandwidth:PC3-12800(800MHz)]=12800/8=1600MHz .Here 1600MHz is the memory MAX frequency. 800MHz is the time clock frequency.