I'm running 32 GB 2x16 3900 MHz 16-16-16-32 1.4v on my z390 Dark. VCCIO and VSA at 1.25v, I put a ton of time into tuning the timings at 3900 so I probably will leave it alone. I'll attach an AIDA64 benchmark.
I have no complaints. If memory speed is important, you need to buy a board with really good memory support. My 7700K ran at 3466, I had it at 3566 at one point on my z270 Gaming 9, but the memory support sucked ass on that board compared to the z390 Dark.
If you want to run 4 sticks at high clock speeds you'll have to choose a board with T Topology memory layout.
Last edited by cerealkeller; 03-19-2019 at 06:25 PM.