RAM speed

[kelrin]

I am thinking to upgrade my RAM.

Here is what Linux tells about my current module:

Handle 0x003C, DMI type 17, 40 bytes
Memory Device
  Array Handle: 0x003A
  Error Information Handle: Not Provided
  Total Width: 64 bits
  Data Width: 64 bits
  Size: 8192 MB
  Form Factor: SODIMM
  Set: None
  Locator: DIMM B
  Bank Locator: BANK 2
  Type: DDR4
  Type Detail: Synchronous
  Speed: 2400 MT/s
  Manufacturer: Micron
  Serial Number: 128BADF8
  Asset Tag: 0F161800
  Part Number: 8ATF1G64HZ-2G3B1 
  Rank: 1
  Configured Clock Speed: 2133 MT/s
  Minimum Voltage: 1.2 V
  Maximum Voltage: 1.2 V
  Configured Voltage: 1.2 V


Why does "speed" and "configured clock Liteblue speed" differ?