XMP on these systems is a bit iffy/dodgy depending on your country of origin. You have to double check it every time. I typically enable it and then go through everything manually.
1. Are you fixing input voltage at 1.8v? I wouldn't. It likely is going to require more than that with 32G >4GHz. Start with that at Auto, but you may need to set it to 1.9 or higher.
Oh and to step back, I've seen very little (no objective) difference between my RVE and X99Pros when it comes to OC, but who knows, the RVE might have a little more headroom here or there. So, the guides here, saving any Rampage specific BIOS settings are applicable.
2. This is specific to each system, but with 32G, I was seeing 1.12-1.18v chosen when Auto and I could never do better manually (different story with 128G - that's 1.22).
3. There are 2 DRAM voltage settings - the one you see on the first page is the boot voltage. There is an "eventual" voltage as well. I typically fix the eventual voltage at the advertised capability of chip. Per the various guides, the boot voltage typically needs some head-room to account for training. Give it an extra 0.01 or 3 (start low, more is not always better).
4. Check all the timings in the SPD readout. It is often pretty incomplete, but use whatever it will give you to fixup the memory timing
5. In digi+, try the "extreme" settings in the phase tuning.
6. I typically start all my OC at 1.3 and work down (core and cache). You may (I have) found that uncore/cache voltage impacts the memory controller's ability to handle higher rates pretty drastically. It may not be linear, but short version is that for any given OC, it needed a little more when the ram was also clocked higher. Oh and offset only in the cache voltage, not adaptive (cpu adaptive is fine, but will require more stability testing). I don't know if they ever fixed that, but adaptive has never worked fo rme.
7. I've always started my XMP exploration after f5 defaults on everything else to learn what the DDR wants on its own. x99 + XMP is a "suggestion" not a promise (putting it lightly - I've not had a single one work out of the box).
8. if all else fails, dial back to 2666 (not 2133) and start working those headline numbers 16-18-18-36. Drop them each by one to start and then see where it leads you... (there is some math to be aware of there - check the sticky on this forum (modern memory timings or something to that effect).
