Thanks for the heads up on 1303. I've just tested it and it did not improve on my 3600MHz stability. Nevertheless, I leave it installed for now.I am running 8 x 8GB DIMMs for a total of 64GB.
Looking at your RAM's timings I'm pretty sure that those are NOT Samsung B die modules. (somebody please correct me if I'm wrong) This is probably why your DIMMs are getting so hot and my don't. Having in mind this and the 8x 32GB configuration you are running, I'm thinking that anything more than 3200MHz is a bonus! 256GB is the maximum supported memory for a Threadripper chip, and even according to the board's manual, the fastest supported speed at this config (8X32GB) is 3200MHz. Another thing is that a 32GB RAM Stick is at best a Dual-rank module (or even a Quad-rank if you are not lucky). That many RAM banks are quite hard for the memory controller to deal with. This makes things unstable at higher frequencies...
One last thing you can try is to update your BIOS to 1303 (it was mentioned earlier here in the thread) This one is not yet on ASUS'es website for some reason but it's not a BETA one (at least to my knowledge).
I've also tried to run my RAM desynced at 1800MHz FCLK with RAM at 3466MHz. In my short testing (about 10 minutes) it seems to be stable. If I run it at 1733MHz FCLK with RAM at 3600MHz, AIDA64 failed in less than 2 minutes. If the RAM weren't tested previously at 3600MHz on an ASRock overnight, I would have concluded that the RAM is at fault.
I will leave it at 3466MHz for now and tighten the timings unless I am in need of more speed than capacity than I will reduce to 128GB and run the rig at 3600MHz.