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The original Ryzen (1000 series) shipped plenty units with hardware defects that could be exposed by running parallel compiles. The so-called segfault bug: htt

• ComputerGuru 7y ago
  From your link: > AMD has confirmed this issue doesn't affect EPYC or Threadripper processor The CPU Michael was using was a Ryzen 7, not a Threadripper. But I don't know if TRs were later found to have the same problem, which wouldn't surprise me.
  • paulmd 7y ago
    IMO the likely cause was some kind of cache bug due to manufacturing. Threadripper processors were binned for tighter cache timings (they had the same timings as the 2000 series desktop chips) and thus didn't suffer from it. EPYC was on a different stepping entirely and didn't share dies with the consumer or HEDT processors. I suspect they likely had the tighter cache timings although I'm not sure on that. Regardless, it's also possible that they were just binned out, or nobody ever encountered it. EPYC was not a very high-volume product, most people did test installations and said "yeah, we'll wait for Rome". Quad-numa on a package and lower-than-Intel IPC on a pretty poor node was not a winning formula. Once the problem was realized, desktop Ryzen processors started getting binned for it as well. A few slipped through here and there, so it wasn't a manufacturing change, I think binning is the most likely explanation.