2nd Gen AMD Ryzen Supported RAM SpeedsWritten on June 6, 2018 by Matt Bach
While not widely known, the supported RAM speeds for AMD's original Ryzen CPUs varied based on a number of factors including the number of sticks you are using and whether the RAM was single or dual rank. This information was not listed on most specification pages, but was available in a few official posts including Tips for Building a Better AMD Ryzen System.
The newer 2nd Gen Ryzen CPUs also have many of the same RAM speed limitations, but unfortunately AMD only lists a "Max System Memory Speed: 2933MHz" on their CPU specification pages and, unlike the original Ryzen CPUs, there are no other public documents from AMD that list the various RAM speeds that are supported. However, we reached out to our contacts at AMD and they were able to send us the following chart showing the officially supported RAM configurations for the 2nd Gen AMD Ryzen desktop processors:
In other words, for users that want to use four sticks of RAM, DDR4-1866 or DDR4-2133 is the fastest supported RAM speed depending on whether the RAM is single or dual ranked. If you only need to use two sticks of RAM, the supported speed varies between DDR4-2400 and DDR4-2933 depending on a wide range of factors including the memory rank, the total number of RAM slots on the motherboard, and the number of PCB layers your motherboard has.
One thing we do want to mention is that we also confirmed with AMD that using RAM that is outside this official specification will not void your warranty. This is simply AMD's recommendations based on what they know and have tested to be stable.