Dual/Single RANKED Setting

skeletonw00t

skeletonw00t

skeletonw00t

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Joined
8 Jan 2007
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221
Hi,

Bit of a weird one here on "ranked" memory settings.

Basically I have:
GA-Z170-Gaming K3
16Gb Corsair Vengeance PC3000 Ram

All working fine no issues etc. Then I decided to upgrade the existing 2x 8Gb SPD's to 2 more - so now I have 4x 8Gb PC3000 rams - I checked they were exactly the same model before installing etc.

All boots / loads & doesnt appear to be any issues; however , strangely, on CPUID if I go to the DIMMS 2/4 (new sticks) it says their "ranks" are single, whereas the others are dual.

I know ranks is different to the dual-channel memory setting, but i didnt know of any reason why these settings would be different & also the fact they are working with different settings.

Anyone had this before?

Cheers
 
Single/Dual Ranked is the physical layout of the memory modules on the PCB. Single Ranked only have memory chips on one side, Dual Ranked have memory chips on both sides (it's actually slightly more complicated than this, as it's more to do with how the modules are connected).

So for example a 8GB module may be made of 4 x 2GB modules in a single rank, or it could be 8 x 1GB modules in a dual rank configuration.

So there's no setting you can change that will affect this. It will just be that they changed the manufacture process of the modules based on parts availability/cost over time.
 
HeX said:
Single/Dual Ranked is the physical layout of the memory modules on the PCB. Single Ranked only have memory chips on one side, Dual Ranked have memory chips on both sides (it's actually slightly more complicated than this, as it's more to do with how the modules are connected).

So for example a 8GB module may be made of 4 x 2GB modules in a single rank, or it could be 8 x 1GB modules in a dual rank configuration.
Click to expand...
Rank isn't about physical number of memory chips, or if they're on single side or on both sides.
Having chips on both sides is just result of only 8 chips fitting onto one side. (without making DIMM taller)
Number of ranks is about bit "width".

Memory channel is 64 bits wide and memory must be added into it in "wholes" making 64 bits.
And DDR4 chips are normally 8 bits wide, which means 8 chips per rank. (in non-ECC DIMM)
If you have 2GB chips those would have to be 16 bit wide, or minimum DIMM capacity you can achieve is 16GB.

And either because of unavailability 1GB chips at the time, or it being older design DIMM, they couldn't fit 8GB into single rank in older DIMMs:
If you have ½ GB chips you need 16 of them to make 8GB DIMM.
And if those were 8 bit wide chips that makes 128 bits meaning two ranks.
That 1GB chips size is also why most 16GB DIMMs are dual rank modules.
2GB chips simply aren't used commonly in consumer memory yet.

For servers needing higher capacity there are also quad rank DIMMs with four times the number of chips and capacity than single rank DIMM using same chips.
And in servers having more DIMM slots there's also some limit of how many ranks memory controller can handle per channel:
If it can handle 8 ranks per channel while having four slots per channel that can be maxed multiple ways:
1x quad+2x duals leaving one DIMM slot empty.
1x quad + 1x dual + 2x single rank modules
Or 4x dual rank modules.
 
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