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ECC matters

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Re: ECC matters

#111
post #10

I bought ECC RAM for my laptop and it definitely was about 4x the price. It's valuable to me for a few reasons -- peace of mind being a big one. Bit flips happen and are real. I really wish ECC was plentiful and not brutally expensive!

This is the first time I hear about a laptop that supports ECC memory. Could you please share the make and model?

Lenovo (P series) and HP workstation models also support ECC

Re: ECC matters

#112
post #100

Earlier quoted context omitted.

I don't think Threadripper is a hard requirement for ECC. There's some pretty reasonable TDP processors if you step down from Threadripper.

I haven't seen definite details and test results on these (but haven't looked recently). What specific configurations (CPU, MB, RAM) are known to work? Let's say I have a Ryzen system, how can I check if ECC really works? Like, can I see how many bit flips got corrected in, say, last 24h?

Every Ryzen (non APU) supports it* Check the montherboard of your choice, they would declare it in big bold letters, e.g.[0]

*not officially, and the memory controller provides no report for 'fixed' errors.

0: http://www.asrock.com/mb/AMD/X570%20Taichi/

Re: ECC matters

#113

ECC works if done right. Accessing a memory location can fix bit-flips (ECC is a 'correcting' code). But systems that don't regularly visit every memory location, can accumulate risk. Those dark corners of RAM can eventually get double-bit errors and be uncorrectable. So an OS might 'wash' RAM during idle moments, reading every location in a round-robin manner to get ECC to kick in and auto-correct. Doesn't matter ho…

Interesting, similar to scrubbing raid arrays. How often do those double bitflips appear though? You'd have to have a pretty long running server for that to be a problem, no?

Re: ECC matters

#114
post #66

Earlier quoted context omitted.

I've considered using an AMD CPU instead of Intel's Xeon on the primary desktop computer, but even low-end Ryzen Threadripper CPUs have TDP of 180W, which is a bit higher than I'd like. And though ECC is not disabled in Ryzen CPUs, AFAIK it's not tested in (or advertised for) those, so one won't be able to return/replace a CPU if it doesn't work with ECC memory, AIUI, making it risky. Though I don't know how common i…

I don't think Threadripper is a hard requirement for ECC. There's some pretty reasonable TDP processors if you step down from Threadripper.

It’s not. I have a low end Epyc machine with ECC. It has a TDP of something like 30 watts.

Re: ECC matters

#115
I have trouble parsing information from this rant. Is someone willing to translate this into an argument (a string of facts tied by logical steps)?

Re: ECC matters

#116
post #66

Earlier quoted context omitted.

I've considered using an AMD CPU instead of Intel's Xeon on the primary desktop computer, but even low-end Ryzen Threadripper CPUs have TDP of 180W, which is a bit higher than I'd like. And though ECC is not disabled in Ryzen CPUs, AFAIK it's not tested in (or advertised for) those, so one won't be able to return/replace a CPU if it doesn't work with ECC memory, AIUI, making it risky. Though I don't know how common i…

> but even low-end Ryzen Threadripper CPUs have TDP of 180W, which is a bit higher than I'd like. Why does it matter? It doesn't idle that high; it only goes that high of you're using it flat out, in which case the extra power usage is justified because it's giving that much more performance over a 100 W TDP CPU. Now I totally get it if you don't want to go Threadripper just for ECC because it's more expensive , but…

I prefer to pick PSU and fans (for both CPU and chassis) that can handle it comfortably (preferably while staying silent and with some reserve) with maximum TDP in mind, and given that I don't need that many cores or high clock speed either, a powerful CPU with high TDP is undesirable because it just makes picking other parts harder. I've mentioned TDP explicitly because I wouldn't mind if it was a (possibly even high-end) Threadripper that somehow didn't produce as much heat. Although price also matters, indeed.

Re: ECC matters

#117
post #66

Earlier quoted context omitted.

I've considered using an AMD CPU instead of Intel's Xeon on the primary desktop computer, but even low-end Ryzen Threadripper CPUs have TDP of 180W, which is a bit higher than I'd like. And though ECC is not disabled in Ryzen CPUs, AFAIK it's not tested in (or advertised for) those, so one won't be able to return/replace a CPU if it doesn't work with ECC memory, AIUI, making it risky. Though I don't know how common i…

> but even low-end Ryzen Threadripper CPUs have TDP of 180W, which is a bit higher than I'd like. Why does it matter? It doesn't idle that high; it only goes that high of you're using it flat out, in which case the extra power usage is justified because it's giving that much more performance over a 100 W TDP CPU. Now I totally get it if you don't want to go Threadripper just for ECC because it's more expensive , but…

>> I've never seen anyone shop a desktop CPU by TDP, rather than by performance and price.

Oh oh, me! Back in the day I bought a 65W CPU for a system that could handle a 90W. I wanted quiet and figured that would keep fan noise down at a modest performance penalty. It should also last longer, being the same design but running cooler. I ran that from 2005 until a few years ago (it still run fine but is in storage).

Planning to continue this strategy. I suspect it's common among SFF enthusiasts.

Re: ECC matters

#118
post #74

Good news is that for DDR5, ECC is a required part of the spec and should be a feature of every module: https://www.anandtech.com/show/15912/ddr5-specification-rele...

On die ECC is great for increasing reliability, if all else is equal, but if it doesn't report to the memory controller, and if the memory controller doesn't report to the OS, I think it will be worse than status quo, because all else won't be equal. With no feedback, systems are going to continue to run on the edge, but now detectable failures will all be multi-bit; because single bit errors are hidden.

Re: ECC matters

#119
post #2

“ECC availability matters a lot - exactly because Intel has been instrumental in killing the whole ECC industry with it's horribly bad market segmentation.” Its. There, I finally corrected Linus Torvalds in something. :))

How is your Finnish?

Or Swedish for that matter, as I believe Torvalds maternal language is Swedish

Re: ECC matters

#120
post #74

Good news is that for DDR5, ECC is a required part of the spec and should be a feature of every module: https://www.anandtech.com/show/15912/ddr5-specification-rele...

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