Which Linux utility can tell me if I have registered or unbuffered ECC memory in my server? Lshw and dmidecode do not work for me; dmidecode provides no information about registered vs. unbuffered:

Handle 0x0022, DMI type 17, 28 bytes
Memory Device
        Array Handle: 0x0021
        Error Information Handle: Not Provided
        Total Width: 72 bits
        Data Width: 64 bits
        Size: 4096 MB
        Form Factor: DIMM
        Set: None
        Locator: DIMM-1A
        Bank Locator: Not Specified
        Type: <OUT OF SPEC>
        Type Detail: Synchronous
        Speed: 1066 MHz (0.9 ns)
        Manufacturer: Not Specified
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Part Number: Not Specified
  • 1
    I didn't even know you could get this much info Apr 2, 2011 at 18:15
  • Neither did I. I wanted to know if my RAM was ECC.. and came to know that it can be detected using "dmidecode"
    – Pankaj
    Dec 21, 2012 at 4:50

3 Answers 3


Data width = 64 (8 banks * 8 bits)

Total width = 72 (9 banks * 8 bits)

The extra bank indicates that ECC is active.

  • Nice (I hadn't noticed that), but the question was actually registered or unbuffered. Apr 3, 2011 at 11:34

Support for the “Registered” and “Unbuffered” type details (amongst others) was added in dmidecode 2.11 (dmidecode.c revision 1.158). If you get the latest version, I expect it'll show either Type Detail: Synchronous Registered (Buffered) or Type Detail: Synchronous Unbuffered (Unregistered) (and probably Type: DDR3 above).


It's marked as Type Detail: Synchronous So I'm going with Registered. From Newegg's wiki:

Why is "unbuffered" the counterpart of "registered"? Buffers are known as "asynchronous" components, which is to say signals on the input pins appears directly on the out put pins. On the contrary, registers are known as "synchronous" components: new signals on the input pins do not show up immediately on the out put pins. Instead, they wait for the next tick of the system clock.

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