One thing to watch, while I too like the idea of the AE (passive CS cooling), it apparently only has a 128Mb flash chip, so could run into issues with next year's CPU like some boards are seeing with Zen2.
It's mind boggling that they would cheap out on the flash size on such a board.
Go for 2 x 16GB sticks if you can find the right speed at the right price. Then you have less issues with 4 sticks and the option to easily go to 64GB later.
3900X in the house ...
Holy BLEEEP, I wasn't expecting this kind of difference in cache speed!
This is with the same BIOS and RAM settings (actually I think they were tuned a little faster on the 2700X) ....
I just set 16-16-16-38 and 48 for tRC I think it was and the rest on Auto and it's pretty good other than a little loss of read and write but I'm sure tweaking up the sub timings will easily sort that out.
XMP @ 2733MHz didn't boot but I didn't try training it up yet either.
Update: Lots of GSOD, I'm not too happy with the ASRock BIOS, it needs the 1.0.0.3 update IMO ASAP.