Memory kits are designed around the motherboards available at the time. This means a high-end kit from a few years ago may not work as intended on a recently released motherboard, as the new motherboard was not designed to handle how the older memory kit was made.
This issue is mostly present in kits meant for Z170 and X99, and were likely purchased in or before 2017. For example, our VENGEANCE LPX 16GB DDR4 2800MHz memory kit is a kit from around 2017 and has no support for AMD chipsets.
This also applies to trying to use a new high-end memory kit on an older motherboard. Because the new kits are designed for newer generation motherboards, older motherboards may run into compatibility issues even if the motherboards state support for the rated speed.
For example, our VENGEANCE LPX 16GB DDR4 3600MHz memory kit states support for Intel 300 series and above, along with only X570 for AMD. Some B450, X470, Z170, and Z270 motherboards state support for 3600MHz, but that does not mean they are able to run our kit as intended.
If you are having issues getting your memory kit to run at its rated speed, take a look at our help article on the subject for further troubleshooting.