Why Doesn’t DRAM Run At Advertised Speed?
This is probably one of the most frequently asked questions about DRAM these days, especially since, for all intents and purposes, 1600/9 is considered the basic entry-level speed for newer systems.
Motherboards are designed to accommodate nearly any CPU compatible with their processor interfaces. But the capabilities of each CPU's memory controller can vary greatly. To that end, motherboards are designed to start new DRAM to a preset default data rate that any and all CPU/MCs can handle—typically DDR3-1066, DDR3-1333 or DDR4-2133. A few modules default to DDR3-1600 or DDR4-2400, but manufacturers rarely use those options. If you have DRAM faster than the default, it will have to be set up to run at the specified data rate for your particular kit. See the XMP, AMP, DOCP and EOCP descriptions in item No. 5and the configuration in item No. 14.
An exception to this is the new Kingston HyperX Fury line, which employs plug and play and, when installed in a supported motherboard (chipset), should automatically set itself up to run at its maximum data rate, up to and including the advertised specification.
You generally have two options for setting up the DRAM: manually, which many enthusiasts prefer in order to get the highest data rate and tightest timings, or, if you're dealing with a 1600 MT/s or faster kit, through an XMP profile (the Fury line is one of the few exceptions).
With an Intel motherboard and some AMD motherboards, you simply enable XMP in the BIOS and generally select profile one. From there, you are ready to go (if your CPU can handle the given data rate). Not all CPUs can handle every data rate, so you may have to set it up manually.
If you’re using an AMD motherboard, it may support XMP. However, it's more likely that it will have an option for DOCP or EOCP, which takes data from the XMP profile and translates it to the appropriate preset timings of the BIOS. With these motherboards, check the timings when you’re done, as the manufacturers often set them looser (higher than the timings the XMP spec provides for). Tightening them to the XMP profile can provide better performance.