5 ms·

My Dell M6800 RAM has 2 bad bits out of 32GiB (easily found with the wonderful 'stressapptest' tool). I'm not exchanging the DIMMs because of that (besides, it

My Dell M6800 RAM has 2 bad bits out of 32GiB (easily found with the wonderful 'stressapptest' tool). I'm not exchanging the DIMMs because of that (besides, it's of course in the DIMMs which are more difficult to access). When running Linux I mark a MiB around those memory locations to not be used (memmap option). I haven't bothered to do the same when running MS Windows (it seems a bit more complex). Every once in a while that memory is accessed in a way which causes some corruption leading to a fault. I feel a bit guilty about all those senseless bug reports automatically generated and sent ...

popotamonga 6y ago
Is that tool the same as windows memtest? My brand new pc randomly blue screens twice a month with 'corrupted structure' or something like that, i suspect of ram but windows tool said no errors found after a 3 hour test. Cant even put it on warranty because it cant be reproduced easily. Cant afford to just start replacing components. 5000€ lemon.
- Nextgrid 6y ago
  Memtest86+ (http://www.memtest.org http://www.memtest.org) is what hardware enthusiasts use to troubleshoot memory issues despite the built-in Windows memory test being preinstalled and easier to access (no need to boot from a USB, etc) so I'm assuming it's much better than the Windows one.
  - MawKKe 6y ago
    FYI Last I tried memtest86+ (in June?), it had been outdated for quite some time and downright crashed on newer hardware. The non-free alternative called Memtest86 (by Passmark) works just as well if needed.
  - fomine3 6y ago
    Nowadays I use memtest86 that supports UEFI. On Windows, "RAM Test" paidware works well.
- guenthert 6y ago
  There are of course different kind of hardware errors and what appears to be bad memory might be due to some cells being defect or some less-than-perfect bus signals (which then should affect many addresses). In my (limited, perhaps dated) experience (I used it on maybe a few dozen computers), stressapptest (even using the default plain memory test), is much more efficient in finding hardware issues than memtest86+. If stressapptest doesn't find a problem in 30s, memtest86+ won't find any in 24h. I haven't bothered with memtest86+ in years anymore. EDIT: only ever used the free memtest86+ tool, I have no experience with PassMark's MemTest86.
  - segfaultbuserr 6y ago
    > some less-than-perfect bus signals They are also responsible for some mysterious memory compatibility problems in PCs. All PC builders have this experience - on a certain motherboard model, some DIMMs work, some doesn't, but they are all off-the-shelf parts that follow JEDEC standards. Often there are minor variations in electrical characteristics from DIMMs to DIMMs. If the signal integrity on the motherboard is marginal, there will be mysterious problems.
- userbinator 6y ago
  Try Linpack. It's probably the most stressful of anything I've ever seen, and also a very realistic workload (solving linear equations) --- machines used for scientific computing are doing that all the time. It will stress both the CPU and RAM. (Many overclockers hate it and think it's "too extreme" because it causes their otherwise "stable" overclocks to instantly fail. I love it because it shows how an unstable system will sometimes effectively calculate 1+1=3. I don't consider a system stable unless it can pass a full day of Linpack without a single error.)
  - myself248 6y ago
    > Many overclockers hate it and think it's "too extreme" because it causes their otherwise "stable" overclocks to instantly fail. I guess it's okay to game on a system that's right on the verge of failure; what's the worst that happens, your game crashes, maybe you corrupt a drive? Hopefully there's nothing important on it. But I like your regimen for more serious computing.
userbinator 6y ago
I'm not exchanging the DIMMs because of that Why? 1 bad bit, even an intermittent one, is enough for me to condemn RAM. Memory that doesn't remember what was last written is simply not fit for purpose. Even without faulty hardware, most software is already buggy enough as-is.
- guenthert 6y ago
  Because, as stated, the problem can easily be circumvented. Much easier in fact than getting to the DIMMs on the MB (in many other laptops which prioritize low weight and thinness, there wouldn't even be that option unless you're comfortable with a SMD rework station). Agreed, if the memory would be deteriorating (who knows by which process), the device ought to be replaced. It hasn't however in the last three years, so that seems to have been a singular event (not sure if cosmic rays can permanently damage a RAM cell, but those things are tiny now). It's much more cost effective to use software to work around hardware failures, then to rely on (never perfectly) dependable hardware -- compare Google FS vs IBM Mainframe.
  - fomine3 6y ago
    It's fine if you can recognize all corruption but I doubt in this situation.
- myself248 6y ago
  > Memory that doesn't remember what was last written is simply not fit for purpose. IMHO, this means that every memory that's vulnerable to rowhammer and related techniques is defective, and/or has been specified to run at irresponsible refresh timings. No access pattern should ever be able to change the value of bits not being accessed, that is the definition if faulty memory. And I'm astonished that there isn't a class-action or something. "Normalization of deviance" comes up a lot lately. It's like the frog being boiled, we just came to accept that 100% of RAM is defective by design.
  - WrtCdEvrydy 6y ago
    > we just came to accept that 100% of RAM is defective by design. Computing itself is broken. Every product from physical to application state is broken in some subtle way which is then countered by a higher layer having some extra code (or component) to adjust it.

popotamonga 6y ago

Is that tool the same as windows memtest? My brand new pc randomly blue screens twice a month with 'corrupted structure' or something like that, i suspect of ram but windows tool said no errors found after a 3 hour test. Cant even put it on warranty because it cant be reproduced easily. Cant afford to just start replacing components. 5000€ lemon.

Nextgrid 6y ago
Memtest86+ (http://www.memtest.org http://www.memtest.org) is what hardware enthusiasts use to troubleshoot memory issues despite the built-in Windows memory test being preinstalled and easier to access (no need to boot from a USB, etc) so I'm assuming it's much better than the Windows one.
- MawKKe 6y ago
  FYI Last I tried memtest86+ (in June?), it had been outdated for quite some time and downright crashed on newer hardware. The non-free alternative called Memtest86 (by Passmark) works just as well if needed.
- fomine3 6y ago
  Nowadays I use memtest86 that supports UEFI. On Windows, "RAM Test" paidware works well.
guenthert 6y ago
There are of course different kind of hardware errors and what appears to be bad memory might be due to some cells being defect or some less-than-perfect bus signals (which then should affect many addresses). In my (limited, perhaps dated) experience (I used it on maybe a few dozen computers), stressapptest (even using the default plain memory test), is much more efficient in finding hardware issues than memtest86+. If stressapptest doesn't find a problem in 30s, memtest86+ won't find any in 24h. I haven't bothered with memtest86+ in years anymore. EDIT: only ever used the free memtest86+ tool, I have no experience with PassMark's MemTest86.
- segfaultbuserr 6y ago
  > some less-than-perfect bus signals They are also responsible for some mysterious memory compatibility problems in PCs. All PC builders have this experience - on a certain motherboard model, some DIMMs work, some doesn't, but they are all off-the-shelf parts that follow JEDEC standards. Often there are minor variations in electrical characteristics from DIMMs to DIMMs. If the signal integrity on the motherboard is marginal, there will be mysterious problems.
userbinator 6y ago
Try Linpack. It's probably the most stressful of anything I've ever seen, and also a very realistic workload (solving linear equations) --- machines used for scientific computing are doing that all the time. It will stress both the CPU and RAM. (Many overclockers hate it and think it's "too extreme" because it causes their otherwise "stable" overclocks to instantly fail. I love it because it shows how an unstable system will sometimes effectively calculate 1+1=3. I don't consider a system stable unless it can pass a full day of Linpack without a single error.)
- myself248 6y ago
  > Many overclockers hate it and think it's "too extreme" because it causes their otherwise "stable" overclocks to instantly fail. I guess it's okay to game on a system that's right on the verge of failure; what's the worst that happens, your game crashes, maybe you corrupt a drive? Hopefully there's nothing important on it. But I like your regimen for more serious computing.

userbinator 6y ago

I'm not exchanging the DIMMs because of that Why? 1 bad bit, even an intermittent one, is enough for me to condemn RAM. Memory that doesn't remember what was last written is simply not fit for purpose. Even without faulty hardware, most software is already buggy enough as-is.

guenthert 6y ago
Because, as stated, the problem can easily be circumvented. Much easier in fact than getting to the DIMMs on the MB (in many other laptops which prioritize low weight and thinness, there wouldn't even be that option unless you're comfortable with a SMD rework station). Agreed, if the memory would be deteriorating (who knows by which process), the device ought to be replaced. It hasn't however in the last three years, so that seems to have been a singular event (not sure if cosmic rays can permanently damage a RAM cell, but those things are tiny now). It's much more cost effective to use software to work around hardware failures, then to rely on (never perfectly) dependable hardware -- compare Google FS vs IBM Mainframe.
- fomine3 6y ago
  It's fine if you can recognize all corruption but I doubt in this situation.
myself248 6y ago
> Memory that doesn't remember what was last written is simply not fit for purpose. IMHO, this means that every memory that's vulnerable to rowhammer and related techniques is defective, and/or has been specified to run at irresponsible refresh timings. No access pattern should ever be able to change the value of bits not being accessed, that is the definition if faulty memory. And I'm astonished that there isn't a class-action or something. "Normalization of deviance" comes up a lot lately. It's like the frog being boiled, we just came to accept that 100% of RAM is defective by design.
- WrtCdEvrydy 6y ago
  > we just came to accept that 100% of RAM is defective by design. Computing itself is broken. Every product from physical to application state is broken in some subtle way which is then countered by a higher layer having some extra code (or component) to adjust it.