Requesting help to know RANK (single/dual) of my installed memory

[iwalker]

This might help:

A single-rank configuration (DDR3/DDR4 module) has a width of 64-bit while a dual-rank module will be 128-bit wide . However, as a memory channel is just 64-bit wide (same as a single-rank module), the memory controller can only address one rank at a time.

Here is my lshw output:

        *-bank:0
             description: SODIMM DDR4 Synchronous 2667 MHz (0.4 ns)
             product: GR2666S464L19/16G
             vendor: Hitachi
             physical id: 0
             serial: 00000000
             slot: ChannelA-DIMM0
             size: 16GiB
             width: 64 bits
             clock: 2667MHz (0.4ns)
        *-bank:1
             description: SODIMM DDR4 Synchronous 2667 MHz (0.4 ns)
             product: GR2666S464L19/16G
             vendor: Hitachi
             physical id: 1
             serial: 00000000
             slot: ChannelB-DIMM0
             size: 16GiB
             width: 64 bits
             clock: 2667MHz (0.4ns)

so my memory shows a width of 64 bits - so single rank. So the width value is what you need to be looking at.

Also:

Can I mix single and dual rank memory?

Technically, you can, however, there is no guarantee it will run and run nicely . It is highly recommended to buy RAM in a kit rather than mix and matching.

Best would be from lshw to get the same model memory as the one installed - as per the product number if you are unable to be sure of which one to get. Or alternatively, buy two of the same and pull the existing one out and use that elsewhere. Chances are the memory you have in it, can still be bought and then more chance of it working nicely together.