I need to replace the memory in my system and I'm not quite sure how to determine if the memory is ECC or Non-ECC. How do I determine this?

  • 2
    Is there anyting in the handbook of your PC, Usually it is specified there. Otherwise download and install Speccy. This program tells you exactly which hardware you have in your PC, then you can check it. Mar 24, 2015 at 21:23
  • Look up the motherboard manual, or the system manual for your system, and see what is required for your hardware? Use the memory suggestion tools on the various RAM vendors web sites?
    – Zoredache
    Mar 24, 2015 at 21:24
  • 1
    Related: How to tell whether RAM ECC is working? on Unix & Linux.
    – user
    Mar 25, 2015 at 13:18
  • As a general answer to the question - if you're doing home computing (i.e. not building enterprise servers) you are (and should be) using non-ECC. Also helpful: forum.crucial.com/t5/Crucial-memory-for-PC-systems/… Mar 25, 2015 at 13:22
  • 1
    @MichaelKjörling Data integrity at that level is not critical in home-use applications. Parent applications (or the OS) can handle that easily, and ECC memory comes with a small performance overhead. Additionally, virtually all consumer CPUs do not support ECC memory (thus the "should"). Mar 25, 2015 at 15:36

6 Answers 6


For Windows 7 you can run the following command in command prompt:

wmic MemoryChip get DataWidth,TotalWidth

If the TotalWidth value is larger than the DataWidth value you have ECC memory.

Example output:

//ECC Memory
DataWidth  TotalWidth
64         72

//Non-ECC Memory
DataWidth  TotalWidth
64         64

A better way to determine is via the following command:

wmic MemPhysical get MemoryErrorCorrection

This will return a code based on the type of memory installed:

Value Meaning
0 (0x0) Reserved
1 (0x1) Other
2 (0x2) Unknown
3 (0x3) None
4 (0x4) Parity
5 (0x5) Single-bit ECC
6 (0x6) Multi-bit ECC
7 (0x7) CRC
  • 1
    @DanNeely My system (which I know has 8 strips of 4GB ECC) gives 2 values from that command: 6 and 3 on a second line of output. The other command shows 8 lines with 64 and 72 (as expected) and 1 extra line showing 2 and 2. I have never seen that before. Any idea what that means ? For the record: It is a HP XW8600 workstation (Intel 5400/6311 server motherboard.)
    – Tonny
    Mar 25, 2015 at 19:47
  • @Tonny which command are you using? Mar 25, 2015 at 20:04
  • What does code 3 (none) mean? I have no memory installed? Mar 25, 2015 at 20:51
  • 1
    @DavidGrinberg it means your memory doesn't have ECC. Outside of servers and some high end work stations very few computers use it. Mar 25, 2015 at 21:15
  • @KronoS wmic memphysical get memoryerrorcorrection gives 6 and 3. (Windows 7 x64) then wmic memorychip get datawidth, totalwidth shows the 9 lines of output. 8x "64 72" and once "2 2".
    – Tonny
    Mar 26, 2015 at 10:48

For FreeBSD (and probably most Unix like platforms):

dmidecode -t 17

Example output:

# dmidecode 2.12
SMBIOS 2.5 present.

Handle 0x1100, DMI type 17, 28 bytes
Memory Device
        Array Handle: 0x1000
        Error Information Handle: Not Provided
        Total Width: 72 bits
        Data Width: 64 bits
        Size: 2048 MB
        Form Factor: DIMM
        Set: 1
        Locator: DIMM1
        Bank Locator: Not Specified
        Type: DDR2
        Type Detail: Synchronous
        Speed: 667 MHz
        Manufacturer: AD00000000000000
        Serial Number: 00002062
        Asset Tag: 010839
        Part Number: HYMP125P72CP8-Y5
        Rank: 2

The Total Width: 72 bits is the part you are looking for.

More information in detecting this in Linux can be found on our sister site Unix & Linux Stack Exchange.

More information on how error correcting code works can be found in this simple post where I showed how you could use extra bits to detect and correct errors. This is why we have DIMMs which are 64 bits wide (8 bytes of data wide) or 72 bits wide (64 data plus extra bits to store redundant information).

19.07.2022 - Minor update now that ECC DDR5 is out. DDR5 is not 64 bit normal or 64+8 for ECC. It instead has two 32 bit channels, and more bits are needed for ECC. So expect 80 bits for ECC on DDR5.

  • 4
    dmidecode is standard on Linux, too. I think error correction will happen by default with ECC RAM installed, but if your kernel is monitoring the memory controller to track the memory error rate, that would be another confirmation that you have ECC RAM. (check the kernel log.) Mar 25, 2015 at 8:49
  • How do you check if the memory controller is tracking that? mcelog?
    – Hennes
    Mar 25, 2015 at 10:52
  • I don't have access to any ECC-equipped servers anymore, but I'd look for a kernel log message about it. Maybe there isn't one. There's a link to something about it on buttersideup.com (best domain name ever for a project, IMO). Mar 25, 2015 at 11:14
  • 1
    I think you should explain in your answer what to conclude about ECC if Total Width is 72 bits or 64 bits.
    – A.L
    Mar 26, 2015 at 15:02
  • 2
    "The Total Width: 72 bits is the part you are looking for." And what do I do after I've found it?
    – endolith
    Oct 15, 2016 at 21:53

If you look at the physical memory module, ECC will usually have 9 (sometimes more) chips. Non-ECC will have only 8 (or rarely, 8x2=16).

ECC vs non-ECC (Image courtesy of Puget Systems)

  • 7
    @Hennes: You can have 10, but 9 is far more common. The memory is typically split into chunks of 72-bits (8 bits read at once from each of 9 data-chips), with 64-bits of data + 8-bits of error-correction in each chunk. See here for more technical info. Mar 25, 2015 at 21:38
  • 2
    As a more general rule, if the number of memory chips are divisible by 3 then the module is ECC. Mar 26, 2015 at 15:00
  • Count them on both sides.
    – Leo
    Mar 29, 2020 at 4:46
  • When you have 10 (as in my case), it is likely to mean that you have Registered DIMM with ECC. One chip for the buffering (registered) and one for the ECC is how I understand it.
    – Abel
    Jan 15 at 16:45

inxi can do that:

# On this desktop PC non ECC-RAM modules are used, so it outputs `EC: None`:

$ sudo inxi -m -xxx
Memory:    Array-1 capacity: 32 GB devices: 4 EC: None
           Device-1: ChannelA-DIMM0 size: 4 GB speed: 1333 MHz type: DDR3 (Synchronous)
           bus width: 64 bits manufacturer: Kingston part: KHX1600C9D3/4GX serial: B7ED5A53

# This server has 16 GB ECC RAM:
$ sudo inxi -m -xxx
  RAM: total: 15.49 GiB used: 592.6 MiB (3.7%)
  Array-1: capacity: 32 GiB slots: 2 EC: Multi-bit ECC max-module-size: 16 GiB note: est.
  Device-1: PROC 1 DIMM 1 type: no module installed
  Device-2: PROC 1 DIMM 2 type: DDR4 detail: synchronous unbuffered (unregistered) size: 16 GiB
    speed: spec: 2666 MT/s actual: 2667 MT/s volts: 1.2 width (bits): data: 64 total: 72
    manufacturer: HPE part-no: 879527-091 serial: N/A
  • Is the 4 EC: None the value I should be looking for? Mar 25, 2015 at 19:29
  • Just the EC: None. The 4 is part of the previous field (devices: 4).
    – user89623
    Mar 25, 2015 at 21:25

On a Mac you can look in the System Information application to determine ECC status of the Computer and each RAM module.

/Applications/Utilities/System Information

Select Memory on the right pane, under the hardware section.

Then with the "Memory Slots" listing selected. The window below should show an ECC status.

See picture below:

System Information App window

Also as an FYI each RAM slot will have a Status field if there is a problem detected in a RAM module the status will be a value other than "OK"

  • Does "Disabled" mean the ram is non ECC ? it's not quite clear from your answer
    – mounaim
    Nov 14, 2016 at 16:27
  • That's correct a status of "Enabled" would means that he RAM is ECC.
    – MrDaniel
    Nov 24, 2016 at 19:28

You might also try a free app like Belarc. Gives a bunch more info about your system also...

I have used the software a few times. I have no affiliation with this software, but I do know that it is used by some universities.

I can not provided a screen shot of the results because it contains confidential data, but the web site should provide some examples. Its pretty straight forward (and fast), download the file, run it and the results are presented.


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