>> Everyone repeats the statement DDR5 on-die ECC isn’t a replacement for regular ECC, but nobody ever shows data on DDR5 bitflips.

That's because the on-die ECC cannot detect errors in the transmission of data from the DIMMs to the CPU. It seems like on-die ECC is meant to "hide" some level of errors to make less reliable RAM chips appear good. I have no idea if that's a reasonable way to do it, but it seems like it could be misused. Like TFA suggests, we need to know how the two levels of ECC interact.

As TFA says, it is very likely that the hyperscalers continue to make studies about DRAM reliability in their servers, but they do not publish them, either because they believe that such data could be useful for competitors, or, more likely, they might have NDAs with the memory vendors.

When you do not own a great number of servers, you cannot provide anything else except anecdotal evidence.

Because the vast majority of PCs do not have ECC memory, even the companies that have a great number of PCs have no idea about the reliability of the memory used in those PCs, because it is very difficult to distinguish memory defects from the huge number of software bugs.

Moreover, the frequency of memory errors is proportional with the amount of memory you have, so those with tiny amounts of memory, like 8 GB, are much less likely to encounter memory errors than those who have 32 GB or 64 GB of DRAM in their PCs.

I have tried to always use ECC memory in my computers, whenever possible. Even my laptop is an older Dell Precision, with ECC memory.

But I can also offer only anecdotal testimony.

I have also seen cases like that mentioned in TFA, where the existence of ECC allowed to discover that some modules were not seated well in their sockets, so reseating them prevented the reappearance of errors.

I have also seen a case when a laptop was not used for a long time and it was stored in a rather humid place, so the contacts in the SODIMM sockets had oxidized, which resulted in frequent memory errors. Scrubbing vigorously the contacts and reinserting the memory modules solved the problem.

I have also seen many cases where certain memory modules degraded after many years of use, e.g. 5 or more years of 24/7 use, and they began to have frequent errors, e.g. multiple errors per day, even if when they were new the error rate could have been of one error per year or even less.

In such cases ECC was extremely useful, because the DIMM that had become worn out could be identified and replaced and the server could work fine some more years.

i have years and terabytes of ECC DDR4 and DDR5 memories, UDIMM and RDIMM, with edac enabled all this time, and i have literally never once observed a single error correction. however, (1) i built all these computers myself (2) the servers are located on the middle floor a thick, concrete multi-story warehouse-to-office conversion. as others have said, on a correctly built computer, the source of bit flips is cosmic radiation, and there is a lot of mass between these machines and the sky.