I found that my motherboard specifies with Ryzen 3000 processors the dual channel with 4 sticks is supported until 2666 Mhz and with 2 sticks until 3200 Mhz.
I would like to buy 2x 8GB 3600 MHz CL16 XMP RAM now and add 2 more later on if needed. But of course I want these to all work at full speed, would this work or is it limited to 2 sticks dual channel at that clock speed?