Question AMD Processor ECC Memory Support: Why So Hinky?

[chane]

Two years ago I had a custom desktop pc built using this ECC RAM supporting board and processor.
https://www.gigabyte.com/Motherboard/W480M-VISION-W-rev-10#kf
https://ark.intel.com/content/www/us/en/ark/products/212265/intel-xeon-w-1370-processor-16m-cache-up-to-5-10-ghz.html

I chose that CPU for its processing speed but at least as much for its ECC RAM support and (at least for Intel CPUs) its relatively low 80 watt TDP. https://en.wikipedia.org/wiki/Thermal_design_power

It’s been often claimed that AMD processors are more efficient than Intel’s. But which, if any, AMD processors which are comparably fast to the above Intel CPU have 80 watt or lower TDPs-and offer ECC memory support?

I’ve also read at Reddit and at other forums that only the fastest AMD CPUs claim to support ECC RAM, and even ECC error detection from those SKU numbers was found some times to crap out.

How difficult can it be for AMD and for AMD/ECC supporting motherboard brands to get ECC RAM support done right?

And also to offer ECC RAM support for it slower processors?

 

[mikeymikec]

AFAIK ECC RAM is generally considered to be in the realm of pro workstations rather than mainstream desktops. Also (AFAIK, a quick google seems to agree with me), motherboards have to be able to support the feature too.

For example:

[Motherboard] List of AMD Ryzen™ Processors with support for ECC memory | Official Support | ASUS Global

Official name	Support with B550	Support with X570	ECC functions
AMD Ryzen™ 5000 Series Processors	V	V	Supported
AMD Ryzen™ 4000 G-Series Processors	V	V	Support only with PRO
AMD Ryzen™ 3000 Series Processors	V	V	Supported
AMD Ryzen™ 2000 Series Processors		V	Supported
AMD Ryzen™ 3000 G-Series Processors		V	Support only with PRO

Therefore I would expect that boards that are for "pro workstation" processors such as the threadripper, xeon etc are going to much more consistently support ECC RAM.

IIRC doesn't ECC support also slow down RAM access? So it's more of a maximum stability no-matter-what feature rather than maximum performance, rather like RAID1 IMO.

 

[lopri]

All Ryzen desktop CPUs support ECC. But you also need to confirm the support of the motherboard you choose. Most boards will explicitly state in the spec sheet whether they support ECC or not. Of course you also want to make sure they in fact work, not just on paper.

 

[chane]

AFAIK ECC RAM is generally considered to be in the realm of pro workstations rather than mainstream desktops.

That was true until Rocket Lake was succeeded by Alder Lake. Numerous mainstream processors listed in Bold support ECC RAM.

Alder Lake - Wikipedia

en.wikipedia.org

 

[chane]

Of course you also want to make sure they in fact work, not just on paper.

I'll swap in/out a storage drive now and then but building pcs from scratch is not my thing. And I don't even know if my builder would recommend me buying motherboards for him to test for ECC RAM support and which were not returnable. Besides, such confirmation should be the BRAND's job, not the user!!

 

[mikeymikec]

That was true until Rocket Lake was succeeded by Alder Lake. Numerous mainstream processors listed in Bold support ECC RAM.

Alder Lake - Wikipedia

en.wikipedia.org

Actually ECC support in 'desktop realm' processors goes back way further than that, at least as far back as AM3, so my original point remains valid.

I'll swap in/out a storage drive now and then but building pcs from scratch is not my thing. And I don't even know if my builder would recommend me buying motherboards for him to test for ECC RAM support and which were not returnable. Besides, such confirmation should be the BRAND's job, not the user!!

Maybe yes, maybe no. I don't know much about ECC RAM, but my first concern from experience would be that simply listing ECC support without explicitly listing everything that anyone in the ECC biz would consider to be "full ECC support" is one of these classic pitfalls of just going by specs and hoping for the best.

For example, I was looking into duplex printing + scanning support and encountered the general (but not explicitly stated anywhere) policy of manufacturers: If something is explicitly listed in the specs then it works. If duplex scanning is not explicitly listed in the specs, even though say there's an ADF unit on the specs, then it can't do duplex scanning. One might think that the specs should simply say "ADF duplex support: none", but that's not the view the manufacturers take.

So in your case, a board might list that it can take ECC RAM without being able to support all that one think such a statement might imply. For example, with ECC AFAIK the essential feature to make ECC RAM worthwhile is the signalling from the board to the OS that a RAM error has occurred.

 

[DAPUNISHER]

A couple of the new X870e boards have it



I am certain there will be more, if not at launch, via bios update. I also agree the board makers should make it easy for clients to find the info.

 

[bba-tcg]

... Besides, such confirmation should be the BRAND's job, not the user!!

While technically true, caveat emptor.

 

[Doug S]

You shouldn't have to buy the high end motherboards to get ECC support though. There's no reason they couldn't offer it on B840/B850/X870 also, other than being like Intel and relegating ECC support to "premium" markets. Just because the ECC situation on AMD is slightly better than it is on Intel doesn't mean it isn't still terrible.

I'm hoping that LPDDR6 is a major change for both Intel and AMD in that regard, given that you get the necessary bits in every LPDDR6 module (whether soldered or CAMM) so the excuse to limit its support to premium boards/chipsets only would really stretch thin. I mean, in theory phones can do ECC when they go LPDDR6, but I'm not gonna hold my breath on that!

 

[chane]

IIRC doesn't ECC support also slow down RAM access? So it's more of a maximum stability no-matter-what feature rather than maximum performance, rather like RAID1 IMO.

I've read that ECC RAM imposes a speed bump of something like 3% or less. Besides, I do no gaming nor any 4K video editing, so speed is not a priority.

Actually ECC support in 'desktop realm' processors goes back way further than that, at least as far back as AM3, so my original point remains valid.

I've been an Intel user all along so wouldn't know of any vintage ECC supporting AMD processors.

 

[Doug S]

I've read that ECC RAM imposes a speed bump of something like 3% or less. Besides, I do no gaming nor any 4K video editing, so speed is not a priority.

I've been an Intel user all along so wouldn't know of any vintage ECC supporting AMD processors.

People think ECC's penalty is bigger than it is because they look at the fastest ECC DRAM they can buy and compare with the fastest non ECC - it might be a 2 to 1 difference. The thing is, no one is trying to push ECC to high speeds given that data integrity its goal, and many boards supporting ECC don't support overclocking RAM at all so it would be mostly pointless.

With LPDDR6 CAMMs presumably there would be support for overclocking that just like DIMMs. Whether that overclocking would function only when ECC is disabled who knows, but assuming they let you turn it on with ECC enabled I don't see why it should impact the speed the memory can achieve. It would depend on whether the controller can handle that speed with ECC checking enabled. That's just a little added work after the data has been received (to do ECC calculations and verify it is good) so there's no specific reason it should have to impact the bandwidth, but that requires optimizing the controller to hide that additional work which I'll bet no one has ever done with a controller supporting ECC before - because no one was overclocking ECC RAM.

For latency 3% sounds about right, or maybe a little bit more. It adds a cycle or two in the controller to perform the calculation, but most of the overall memory access latency is in the DRAM array and has nothing to do with whether you are getting extra bits for your ECC calculation or not.