For DDR4 rams like 3200mhz 3600mhz, if you install it then boot it up. Most of the time you go to the settings, the rams are running at 2133mhz instead of the speed you expect. You will need to enable XMP for rams to reach the advertised speed.
XMP is like an extension of SPD. Serial Presence Detect. The POST we known is Power On Self Test. It will read and detect all the hardware and settings on the motherboard, and boot them up correctly. All the information are stored in SPD. Dram on the Rams belong to short term storage. Can be wiped. They are stored in the EEPROM, Electrically Erasable Programmable Read Only Memory.
For CPUZ, you can check the SPD on it. Though most of the SPD are locked, there are some people who can edit the SPD. So CPUZ and Thaiphoon might not be able to read the rams accurately.
In CPUZ, the max bandwidth 1067mhz or 1200mhz x2 = 2133mhz and 2400mhz. But the advertised speed is 3200mhz. If look closely you can see XMP-1600 which means 3200mhz when multipled by 2. XMP = Extreme Memory Profile by Intel. MSI has A-XMP, ASUS has DOCP, Gigabyte has EOCP. XMP are tested by the manufacturer. Most of the BIOS will read and run the basic 2133mhz so you need to enable XMP to run the advertised speed for the rams.
Not just adjusting voltage + the mhz is similar to running XMP. XMP are tested by the manufacturers to ensure the rams are stable at such high speed, by tweaking a ton of many things.
Sometimes under BIOS OC, we can see XMP1 and XMP2. XMP1 is more of AUTO mode, letting the motherboard decide the numbers to run the rams at. XMP2 is running the rams at the prefixed numbers. Which is better, it depends on the motherboard and your luck in getting the speedier rams or slower rams. So need to try both to find out which is better.
So SPD is the basic specs of the rams while XMP is the higher specs of the rams stored in the EEPROM of the rams. Always enable XMP when it is available in your BIOS.
