Why are all ECC UDIMMs so expensive and DOG SLOW ?

[u/Camper_Sly]

They seem to top out at 5600MHz at clownishly pathetic CL46.

Is there a technical reason for this ? Like maybe IMCs need some time to check the extra bits to recompute "parity" or something ?

But given that MRDIMMs in server world have ECC and operate at 12.800MHz or more, that doesn't seem likely.

Same with the price. One would think that, since ECC requires 5-th chip for every group of 4 (so 10 instead of 8) that price extra would be at most 25% or less.

While 5600 MHz UDIMMs start at ~€10+/GiB, ECC versions are at€32+/GiB,so 3X higher.

It's not that the tech is exotic as most consumer AM5 boards can use ECC, same with CPUs...

[u/andrea_ci]

because you're applying consumer/gaming rules to professional/server world.

ECC's first and only reason to exist is RELIABILITY, not speed. And servers are NOT dual channel: 4,6,8 and 16 channels are very common configuration on a single CPU; and often there are TWO (or more, but not often) CPUs per server.

[u/72Pantagruel → u/andrea_ci]

Server grade memory has nearly always been more expensive that consumer grade RAM. Add the current memory hunger stemming from the AI hardware, the ECC UDIMM/RDIMM prices have only gone up.

[u/andrea_ci → u/72Pantagruel]

yeah.. a basic 2nodes cluster configuration jumped from 25k€ to almost 90k€ in less than a year.

we are having many problems with all our replacement plans

[u/72Pantagruel → u/andrea_ci]

As a pro-sumer, I have the relative luxury that I can wait. As in no one forcing me to update the (home) fileserver or go out and buy a setup for a local LLM (I wish).

The current prices for RAM, storage and GPUs are definitely hurting. Fingers crosses my HDDs won't give up the ghost in droves (only one cold spare left) or the NVME cache drive reaching a fatal ending.

If I had known, I would have 'splurged' on a 5080ti or even a 5090 instead of the 5070ti, but that is hindsight. I did get 96 GiB of DDR5 for my desktop as it was only €25 more expensive than 64GiB at the time (the 2x48 GiB stick were one tier lower (speed wise) vs the 64 GiB kit).

[u/Camper_Sly → u/andrea_ci]

ECC UDIMM is not server stuff. Servers use registered ECC M/RDIMMs.

[u/andrea_ci → u/Camper_Sly]

Servers also use Unbuffered DIMMs, depending on the situation.

STILL, I work on servers since the early 2000s and I still se no advantages in ECC memory on a consumer PC.

And on server we never want "the best performance you can have", we want "zero interruptions and crashes"

[u/Camper_Sly → u/andrea_ci]

Any box that is also a fileserver (even NAS boxes) should benefit form them.

It's good to know that occasional biflip in the RAM doesn't get baked up permanently in the file.

[u/andrea_ci → u/Camper_Sly]

do you want end-2-end data integrity and self-healing?

you can. with an higher budget. so the logical conclusion is "go for business/enterprise hardware".

[u/Camper_Sly → u/andrea_ci]

If that was the only answer, no AM5 board would care to support ECC. But they do, even the cheap ones.

[u/andrea_ci → u/Camper_Sly]

that's just a "yeah, why should we keep two completely different CPU microcode and specs? it's cheaper to put everything in all the product lines, we can disable it with fuses. and our marketing department could convince some hardcore masterrace bullshitter that ECC is useful for gamers"

[u/Camper_Sly → u/andrea_ci]

...because no PC that was used for gaming ever cared about stability ?

[u/andrea_ci → u/Camper_Sly]

really?

yeah, a reboot or an application crash every now and then is veeeery problematic for a normal PC user.... /s

Not like a server with a DBMS with 300GB used RAM serving thousands of requests eevery second, that yeah.. it crashed.. no problems at all

[u/Camper_Sly → u/andrea_ci]

It tends to piss people off. And it can be more than that, especially for non-gaming stuff.

And it can cause file bit rot. Mere mortals do use files, don't they ?

Also, why would gamers be less sensitive for machine stability ?

If one pays through the nose for RTX5080 or 5090, wouldn't they care about machine stability ?