Having built a few quad/dual cpu AMD Opteron systems since ~2013 with supermicro boards, I can tell you they are extremely sensitive to RAM brands/models and variations. Sometimes even RAM in the verified supermicro list would have issues.

On a side note, it was about then that I foresaw AMD's move towards high core counts and I love what they have been doing both on desktop and in the server space. Honestly though, I think if I were to try to do a newer amd server I might try to push a threadripper if the power profile fit the DC/colo instead of an epyc mostly because of the lanes and the fact that anything I'm doing on a system that powerful is going to have a 40gb+ mellanox and often in combination with GPUs.

The single socket epyc boards expose a lot more PCIe than threadripper boards, from what I can tell.

$/core-ghz is much better on the TR parts though, if you're paying retail. Epyc chips sometimes show up on secondary markets at much better prices than retail. (e.g. my 7742's I basically paid the same $/core-ghz as the current top end threadripper parts).

Yeah it's generally a tradeoff of pci lanes to clock speed between the two. I would go for the clock speeds.

"When I did have memory corruption problems running at higher memory speeds I didn't get a single ECC error, which I found surprising and concerning."

How is this possible?

It's possible because many motherboards and even integrated systems fail to setup EDAC properly at boot time.