[account42]

I think it mainly applies to non-server systems where a) most people don't even know about ECC and b) non-server Ryzens can only use UDIMMs but there are not that many ECC UDIMMs available (probably just because of low demand) so you probably need to make some tradeoffs like paying more (more than +15% markup for the 9th bit) and won't have as fast chips available at the high end.

I think it is also not required for consumer Ryzen mainboards to support ECC but at least for the high end ones many do.

[adrian_b]

Because only some Ryzen motherboards support ECC, one must always read carefully the technical specifications before buying a motherboard.

There are many ASUS and ASRock AM5 (and AM4) motherboards that support ECC, and for those it is typically writen in the memory section "supports ECC & Non-ECC unbuffered DIMMs".

When nothing like this is written, then ECC is not supported.

Moreover, all the motherboards with ECC support must have in the "Advanced" BIOS Setup an option for enabling ECC, which must be used, because the default is always to disable ECC.

With the Ryzen 7000 series there is an improvement over the previous Ryzen series, because in their specification it is written clearly that ECC is supported. Previously, the ECC support was not explicit, even if, unlike Intel they did not disable ECC, so you could hope that it works fine.

Now Intel no longer disables ECC in many Raptor Lake and Alder Lake desktop CPUs, but the motherboards with ECC support for Intel are much harder to find (because they must use a special workstation chipset, while for AMD it is enough to add the PCB traces for the ECC bits).

[simoncion]

> Moreover, all the motherboards with ECC support must have in the "Advanced" BIOS Setup an option for enabling ECC, which must be used, because the default is always to disable ECC.

On both of my Ryzen ASUS motherboards (WS X570-ACE, and ROG STRIX X399-E GAMING) this is not true. I just slapped the DIMMs in there and powered the box up.

dmidecode thinks that the system has ECC enabled:

  dmidecode --type memory | grep -e "Error Correction"
   Error Correction Type: Multi-bit ECC

'amd64_edac' doesn't complain about being loaded on a non-ECC system.

The closed-source version of memtest86 reports that it's running on an ECC-enabled system.

[adrian_b]

This may depend on the BIOS version, even on the same motherboard.

I also have the same ASUS Pro WS X570-ACE (bought in Q4 2019), which I use with ECC DIMMs, and I had to enable in BIOS the support for ECC.

In any case, one should always check for such an option in the BIOS, to avoid surprises.