So for a 1800x people usually take a x370 mainboard, I would look at what features you want to have and then choose according to price/appearance from it if you have chosen a mainboard.If you have chosen a mainboard then look for the compatibility list and depending on the ram you want you can choose one with this speed (on the list) if you tell me your desired mainboard I can do it for you.

I don't have a Ryzen 7 1800X processor, but here: http://www.corsair.com/de-de...
you will find all the memory modules from Corsair that have been successfully tested.
You can actually use any mainboard with the AM4 socket. These would be the B350 and X370 chipsets. Depending on whether and how much you want to overclock, you should make sure that the voltage converters are cooled sufficiently.