Ask HN: ECC Memory vs. DDR5 for Stability?

https://news.ycombinator.com/item?id=40687605

by giantg2 • 2 years ago

4 4 2 years ago

news.ycombinator.com

I'm looking into building a new computer soon. With DDR5 having single bit error correction, is ECC memory worth it for desktop computers? I tend to keep my machines for a long time and tend to notice some instability as the memory gets older (seems to be memory in at least 1 case as changing the memory helped). I was planning to do ECC this time, but DDR5 sounds like it could be good enough for me. I'm wondering if anyone has any input on that.

sandreas• 2 years ago

I would recommend to read the "ECC Matters"[1] comments. All you need to know.

1: https://news.ycombinator.com/item?id=25622322

aborsy• 2 years ago

ECC is always preferred if one could afford it.

toast0• 2 years ago

It's not ECC vs DDR5. There are ECC DDR5 Dimms and non ECC DDR5 Dimms. It's a bit complex because DDR5 has internal ECC, but that doesn't protect against errors on the datapath between the RAM and the memory controller (embedded into the cpu), and it doesn't have a mechanism to report errors AFAIK.

ECC without reporting puts you in a weird place where the observable error rate is less, but any observable error will be a multi-bit error. With reporting, you would likely replace a dimm that regularly has single bit errors, and your system would typically halt on any two-bit errors, and three or more bit errors may or may not be detected. Advanced operating systems may let you kill only the processes affected by the two-bit errors, but afaik that's only for mainframes and maybe commercial unix (Solaris? AIX?).

giantg2• 2 years ago

Ah, I see, the data path makes sense. I'd definitely perfer the ECC then. Thanks!

Ask HN: ECC Memory vs. DDR5 for Stability?

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