More than likely, like everyone else, you are encountering the general memory issues that x399/threadripper has been having.
Mostly.. dont use DOCP.. probably wont work.
Try manually setting the ram speed and timings for your ram (although if its ram rated higher than 3400 probably wont work period, that seems to be the speed ceiling for now) and try and get the voltage somewhere between spec 1.35 and 1.4.
Also try with 4 sticks (if you have 😎 as the 8 stick speed ceiling is currently around 3000 depending on the ram.
Ex: I have the 3600 F4-3600c16q-GTZR from Gskill, 32g 4x8, running at 3333 at 15-15-15-35-50 CR2T at 1.352 volts (set to 1.27 in bios). VDDSOC around 1.1 (set to .975 manual in bios) and that is so far been working and booted for 6days + on bios 0801.
You will just have to learn to tweak with this stuff more than your intel systems, for now.