[nahuel0x]

Something important not discussed here is that you need not only error correction (when possible) but also error reporting, so you can know you RAM is failing. Sadly, is not possible to get DDR5 on-die ECC error counts reported to the OS. Alternative solution, use IBECC with DDR5, where the CPU reserves a portion of the RAM for parity bits and does the check / reporting.

[inigyou]

My Linux installation came with an AMD MCE driver that reports them to dmesg. It logs a few corrected errors a day.

[adrian_b]

A few errors per day seems much too frequent, unless you live at a high altitude.

Normal good DIMMs, at least when new, should not have errors more frequently than one error per many months.

Frequent errors may appear with memories that are not seated well in their sockets, or which are old, at least several years old.

Frequent errors may also be caused by more general computer problems, like a bad power supply unit.

[etbe]

Does this imply that the all plastic gamer PCs (that are more designed to be art projects than serious computers) are bad and that everyone should be using systems with solid steel cases to block radiation?

[adrian_b]

A steel case has too little effect on cosmic radiation, but it is good to shield electrical noise.

The computers in plastic cases can sometimes be affected by appliances with electrical motors that are used nearby them.

The cosmic radiation is attenuated only inside a big building, e.g. one with many stories above you. A really great attenuation is obtained only underground.

[etbe]

Good point. Some googling suggests that plastic may be better than metal as hydrogen absorbs high energy protons without generating secondary radiation.

[scheme271]

Plastic cases might actually be a bit better than steel depending on the radiation type. Neutron radiation is more effectively shielded by interacting with light atoms so stuff with lots of hydrogen atoms like water or polymers have a better chance of interacting with neutrons and slowing it down so that it can be stopped. Steel is probably better for gamma radiation or charged particles like muons.

But overall, pc cases are probably too thin to appreciably affect the radiation levels. Cosmic rays and their secondary radiation is fine with going through buildings so a 1mm thick case isn't going to do much.

[fvwqcecvq]

Are DIMMs (a.k.a. UDIMM) still a thing?

I would think most servers and workstations would be RDIMM (Registered DIMM) by now and consumer stuff uses soldered down memory. Memory failing because it's old is definitely a thing, and very possible in this scenario, but I feel like I haven't seen errors due to physical insertion, that were not caught immediately by POST, in years.

But maybe it's just me. Happy to be lucky. :)

[wtallis]

The client/consumer desktop market hasn't actually disappeared, and soldered memory is almost unheard-of in that market segment.

[bikelang]

Curious to learn more here - why would altitude play a role here? And when you say high altitude - are we talking La Paz, Bolivia (~12k feet) or Denver, CO (~5k feet)?

[dsr_]

The primary source of uncorrelated bit-flips is, effectively, cosmic radiation.

(Correlated bit-flips are likely from a manufacturing error... or, at least in one case, from excessively radioactive ceramic packaging.)

The more atmosphere you have to randomly absorb high-energy photons, the better.

Higher density memory drops fewer electrons in each well, which means a lower-energy photon can change the state.

Corolary: submarine datacenters are much better than orbital datacenters. Cheaper to cool, construct, shield and access.

[willis936]

>The primary source of uncorrelated bit-flips is, effectively, cosmic radiation.

This gets said a lot but with little evidence. The mario speedrun bit flip has been replicated with marginal connector insertion.

https://youtu.be/vj8DzA9y8ls

[metadat]

Engineering computer memory to work in space is a whole field of study, see Radiation Hardened memory. The main physical difference about space is the radiation profile and radiation induced memory upset.

Are you disputing that the Earth's atmosphere absorbs and reduces the amount of ambient cosmic radiation? Or where is the skepticism coming from?

[adrian_b]

There is a lot of direct evidence from increased error rates in computers on airplanes.

[wmf]

AFAIK it's been documented by Los Alamos since they're at high altitude.

[tliltocatl]

> Corolary: submarine datacenters are much better than orbital datacenters

Yea, except datacenters also need connectivity. And submarine connectivity, while not particularly expensive, is quite vulnerable - even more so than on land.

[etbe]

People outside the US have a significant lack of Internet functionality when there are problems with submarine cables, but it hardly ever fails. Apart from when certain countries sabotage things.

If you only need 100M deep water then you don't need to go far offshore, there are places where it's only about 1KM out. 12M of water is used for storing spent nuclear fuel assemblies and less than half of that is needed for protection so 5M should be adequate for stopping cosmic rays and that depth is common in harbours for recreational boating, such harbours shouldn't have issues of cable breakage.

But the real issue for comparing submarine and orbital computers is cooling. Space is cold but doesn't allow easy transmission of heat.

[exmadscientist]

FYI, it's not so much photons (gamma rays) as muons.

Muons are nasty little buggers.

[eth0up]

If only they were as easy to detect as morons. One is easily detectable with a single glass of beer and nothing more. The other, however, needs dry ice, or a pint of beer on a slab of dry ice.

[loeg]

Check if those are all coming from DIMMs, as opposed to other subsystems (on-die caches).

[etbe]

https://www.theregister.com/on-prem/2021/06/04/fyi-todays-co...

Google and Facebook report a few unreliable CPU cores out of thousands of systems. Meaning maybe a 1/10,000 rate of repeatable CPU errors.

https://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf

Google reports 8% of DIMMs being affected by errors. While the differences in metrics prevent comparing the two things directly it seems that DRAM errors are more common than CPU errors.

[sliken]

Sounds like an issue with hardware. I watch ECC errors for 2500 servers and see a few some days, and zero others. Said servers at an elevation of 6,000 feet or so. A few per day for a single machine is crazy high. You likely have a dimm, dimm slot, motherboard, or CPU issue that's susceptible to RF noise, vibration, temp changes or similar.

[rubatuga]

Isn't that a lot? I see them only when heavily over clocking .