There are two types of ECC memory:
Unbuffered- Basic memory with up to 32GB DIMM modules
Buffered (but rather called Registered due to buffering with "register")- up to 512 GB per DIMM with latest LRDIMM modules.
But capacity isn't main differenciator, the registered modules are the ones with higher stability and reliability, there is little benefit with the unbuffered ones outside of being the minimal required compatible sets with server-class based workstations (Epycs and Xeons don't run with non-ECC kits at all).
TRX40 boards only support the former, unbuffered memory, not registered. And there is absolutely no benefit of going that way because you will loose a bit of performance (ECC memory needs to run at their respective JEDEC standard, which would be 3200/CL22 as the fastest available right now on market).
But even if you were on Epyc which does support Registered modules, the higher stability wouldn't manifest in any way for Corona rendering, these are strictly server features that are necessary for mainly scientific workloads, not ray-tracing CGI.
