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About RAM for laptops I did realize that is available

  • ECC
  • Non-ECC
  • Buffered
  • Unbuffered

It according with:

That options appears on newegg it for Laptop Memory (only about ECC) and Server Memory (about ECC and Buffered/Registered)

Question(s)

With what command or commands is possible to know

  • If the current RAM installed by slot is ECC/Non-ECC and Buffered/Unbuffered?

Observation(s)

In the Ram's box and in the ram itself, there are no indications of these 2 features. Furthermore for some old models, based on DDR2, does not exist this information in the Web.

Goal

The purpose is do a check if the current RAM installed is the correct and do the correct upgrade of RAM.

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    Nitpick: You almost certainly do not need this per-slot. Buffering has to be matched, because it changes some of the electrical characteristics (and for a laptop, I can pretty much guarantee it’s unbuffered), and ECC status generally will be matched too (and if it’s mixed, it doesn’t matter which you pick). Commented Oct 2, 2023 at 10:50

1 Answer 1

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Run dmidecode -t memory.

Handle 0x001A, DMI type 17, 40 bytes
Memory Device
    Array Handle: 0x0019
    Error Information Handle: Not Provided
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 16384 MB
    Form Factor: DIMM

If total Width > Data Width the stick is ECC:

Handle 0x004D, DMI type 17, 34 bytes
Memory Device
        Array Handle: 0x004C
        Error Information Handle: Not Provided
        Total Width: 72 bits
        Data Width: 64 bits
        Size: 8 GB
        Form Factor: DIMM
        Set: None
        Locator: DIMMA1
        Bank Locator: P0_Node0_Channel0_Dimm0
        Type: DDR3
        Type Detail: Synchronous
        Speed: 1600 MT/s
        Manufacturer: Samsung
        Part Number: M391B1G73BH0-CK0
        Rank: 2
        Configured Memory Speed: 1600 MT/s

I'm unsure what you mean by buffered.

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    That's just how you notice. The extra bits only serve the error correction. Commented Oct 2, 2023 at 0:54
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    @tink "buffered RAM" refers to the address lines being buffered electrically, i.e. locally put though a chip that contains a register for each line and typically also clock cleanup circuitry. "Buffered" is a misnomer (we're no longer using EDO-RAM), because the signal doesn't get amplified, but written to a register from which it is read and sent to all attached ram chips on the module one clock later. Anyways, "buffered RAM" is an anachronism synonymous with "registered RAM modules". Don't know whether the Mainboard could even know that. But you'd see it in the type name that'd end in "R". Commented Oct 2, 2023 at 1:03
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    Also, ordinary memtest won't detect intermittent problems with ECC due to the correction. But it is possible: hardware reports everything errors via EDAC interface. You can obtain this verbose information using edac-util. Commented Oct 2, 2023 at 5:01
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    @MarcusMüller In DDR4 and 5, there's two levels of register/buffering. registered DIMMs (RDIMM) register the clock and address lines. Load-reduced DIMMs (LRDIMM) add register the data lines as well. This allows higher capacity via higher data line loading using stacked die packages. RDIMMs cannot be mixed with LRDIMMs.
    – user71659
    Commented Oct 2, 2023 at 16:50
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    sudo dmidecode --type memory | grep Width | paste --delimiters=' \n' --serial shows only the relevant lines, with total/data width for each stick on a single line.
    – l0b0
    Commented Oct 2, 2023 at 21:38

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