i was wondering if someone could help me out find the fastest Ram for my motherboard , i have Z390 Auros pro and I9 9900k , this is my QVL support list link https://download.gigabyte.com/FileList/Memory/mb_memory_z390-aorus-pro_191108.pdf , the thing i want to know is if i find say DDR4 4000MHz and it says under density 8gb , does that mean MOBO only supports that amount of that stick or could i buy two of those to equal 16gb and would it work ? thanks for help ahead of time.