I decided to get a 64GB Kit (4x16GB) for my 1920X. Yes I do use that much ram. Usually in the 40GB range, but its more than the 32GB (4x8GB) I had previously. In any case, the biggest hurdle was finding compatible ram. I guess I was extremely lucky with the 3200 CL14 kit, because it ran flawlessly. But It was only 8GB single sided dimm, which is most likely why I had no problems.
From my online research, even though AMD has updated AGESA for better ram support, there is a lot to be desired. Dual Sided (DS) ram in all the slots (8x) never works above 2666 (if that) and doesn't always see 8 dimms every time. So unless you need 128GB on a AMD system, its not the best idea. So that left me with 8x 8GB (Single Sided) which also seems to have issues reaching a higher speed like 2933 and possible loss of dimms issue also. So that left me with only 1 option for a 64GB Kit if I wanted semi hassle free 3000-3200 64GB Kit.
Which lead me to my next problem. I didn't realize TR4 doesn't like ANY dual sided dimms. At least for the first gen Threadrippers that is. Even though its 8 dimms slots, the Threadripper is basically a 4 dimm system if you don't want a lot of headaches booting and manually tweaking everything. But because DS dimms aren't very compatible, you are kinda limited to 32GB (4x8GB) kits if you want to go above 2933.
Anyways I ended up getting Gskill F4-3733C17Q-64GBTZKK (3733 CL17 4X16GB) off ebay because someone was selling it cheaper than any new 3200 CL16 kit and it was guaranteed Samsung B-Die memory. Which many CL16 kits are not and TR hates none Samsung B-Die from what Ive read (yes even now).
I knew it was never going to boot at 3733 or even 3600, but I figured 3200 CL14 would work. Well I was wrong. even with the extremely loss timings, 2933 is the highest my system will go with DS sticks. That being said I tighten the timings down to CL14. What I didn't know is AMD memory controller is only even numbers so I can't do CL13, only 12,14,16,18, etc. CL12 won't boot (as expected) so I'm stuck with CL14-14-14-34. On the plus side I got Samsung B-Die and I actually saved money over buying a 3200 CL16 kit that most likely won't boot higher than 2933 either.
So to take away from this is AMD TR still have seriously memory issues to deal with and if you are going DS sticks (16GB modules), don't waste money for anything over 2933. I don't think a BIOS update will fix this, only a new memory controller design, so here hoping Ryzen 3 fixes this.