Good news for those of you who are planning to a build a new system around one of AMD's Ryzen processors. AMD updated its list of compatible DDR4 memory with some new entries, giving you a wider selection of RAM to choose from if you want to avoid rolling the dice with an unknown kit.
Normally that is not a problem—so long as you're not trying to install an ultra-cheap memory module that you picked up from some dude in a trench coat on a street corner (along with that Rolex), DDR4 RAM should simply work in any motherboard with DDR4 DIMM slots. However, things have not played out that way.
As we noted a few months ago, Ryzen feels incredibly finicky when it comes to DDR4 memory. Modules do not always boot up at the correct (advertised) speed, leaving you to manually enter the correct parameters in the BIOS and then hoping for the best.
Some memory chips seem work better than others. AMD is aware of this and has been working with motherboard makers on updated firmware to improve the situation. If you are building a system around Ryzen, you'll want to make sure you've downloaded the latest BIOS, which should contain AMD's AGESA 188.8.131.52 micro-code update.
AMD's newest micro-code is primarily aimed at improving memory support. It includes over two dozen new parameters to improve compatibility, which is probably part of the reason why AMD was able to flesh out its list of kits that are known to work. The list includes memory modules and kits ranging in speed from DDR4-2133 to DDR4-3200.
For your best shot at success, you can reference AMD's list (PDF) of compatible memory kits and choose one that has been confirmed to work well with Ryzen. That does mean you can't stray away from the list—you can, but your mileage may vary.