Single rank vs dual rank memory

[Solid State Soul ( SSS )]

Whats the difference between them ?

And do dual rank increase performance over single rank as shown is past LTT and Gamers nexus videos ?

I have a singe rank ram in my laptop with 8 ICs, but i do have a spare dual rank module with 16 memory ICs, should i swap to that one ?

 

[Ja.KooLit]

why dont you try. if you have the stick.

I would try but I dont have stick. wanted after i saw ltt video about it

 

[quanash]

You can watch those videos. Those are a bit more technical than people used to listen, so I hope those will be enough to understand what are the differences and how effects the performance.

 

[freeagent]

Fast single rank is nice, really nice actually.. Some of my best benchmarks came from running fast dual rank. It’s something you can notice in everything.. its smooth..

 

[quanash]

BTW, I forgot to ask and add.

For what system you are asking? If you can give the system specs. We can be much more helpful. The reason I'm asking is, if you have an older system that use DDR4 memory, even if it supports Dual rank 16GB memory, it might not support single rank 16GB memory ( no post nor seeing it 8GB instead of 16GB, due to addressing limitations ).

Also, this Single / Dual rank memory thing is not new, It was there from DDR to DDR4 ( and even before DDR ) memories. Because CPUs and iGPUs performance increased so much and more sensitive to memory performance people start to realize / see performance changes.

If you aren't looking a memory module from;

Samsung, Kingston, Micron, HK Hynix, Nanya ( memory chip manufacturers in short ) you can't find a definitive answer if the memory you are buying is single or dual rank unless you check it visually ( manufacturers like G.Skill, Corsair, Team Group etc. - who are supplying their memory chips from third party manufacturers ) or know what their PCB version numbers means ( like Ver. No: written on Corsair memory's product sticker ).

 

[FreedomEclipse]

1:1 swap in a laptop? I dont think it matters. Run whichever one you want. There wont be any difference in real world performance between the two if both are rated at the same speed as each other. If one module is faster - say 3200 compared to 2400 then go with the faster ram obviously.

 

[GorbazTheDragon]

The number of memory ICs on the stick is not always an indication of the number of ranks... It isn't uncommon to see 16 x4 chips on OEM laptop and server memory (add more for ECC if present), 16 x4 chips increases density per rank, so you can get higher capacity without increasing the rank count and therefore the memory controller loading. (For a 64 bit DIMM you in theory can do anything from 4 x16, 8 x8, or 16 x4 for each single rank, it's just up to the manufacturer to choose which makes more sense for the application in terms of cost, density, and memory controller loading)

It is also very important to distinguish between the performance effects caused by single vs dual rank and those caused by x16 vs x8 or x4 operation. The latter only occurs with DDR4 for example but not with DDR3, DDR2, and from what I've seen it will not happen with DDR5 either. The former can occur in any system which can operate multiple memory ranks and has rank interleaving enabled. Both effects are independent of each other and should produce measurable performance differences in all four permutations.

Dual rank operation provides two main benefits:
- Improved bandwidth/throughput on back to back operations due to rank interleaving (being able to start operations on another rank while the previous is still busy)
- Improved latency under load due to lower probability of bank conflicts (repeated accesses to the same bank) which is enabled by having more independent banks.

These benefits are both bigger when timings are longer, so dual rank generally will have more performance uplift with ICs that do not tighten down well and where JEDEC or slow XMP timings are used.

The downside is higher memory controller load, this can often mean that JEDEC and XMP dual rank kits will have longer timings out of the box than single rank versions of the same stuff, this can offset the performance gains of dual rank somewhat (but will barely ever overcome those gains and cause a performance loss).

The following is an example of the performance benefits of dual rank with XMP and tuned timings.

 

[quanash]

1:1 swap in a laptop? I dont think it matters. Run whichever one you want. There wont be any difference in real world performance between the two if both are rated at the same speed as each other. If one module is faster - say 3200 compared to 2400 then go with the faster ram obviously.

You might wanna watch those videos. Those can change your mind.

 

[Solid State Soul ( SSS )]

You might wanna watch those videos. Those can change your mind.

These are the exact videos that made me aware of single rank vs duel rank matters, it shows that, swapping a single rank dimm with a dual rank one yeilds performance gains!

 

[freeagent]

I saw this one shortly after I built my rig.. I had no plans of running 4x8 until this video..

AMD Ryzen: 4 vs. 2 Sticks of RAM on R5 5600X for Up to 10% Better Performance - YouTube

 

[mechtech]

ya seems Ryzen specifically like 4 ranks total. so either 4 sticks of single or 2 sticks of dual.

Anyone try 4 sticks of dual for 8 ranks total?

 

[tabascosauz]

ya seems Ryzen specifically like 4 ranks total. so either 4 sticks of single or 2 sticks of dual.

Anyone try 4 sticks of dual for 8 ranks total?

Optimal is still 4 x SR or 2 x DR. The speed hit you suffer from 4 x DR is rather disproportionate, and in any case 2x32GB Ballistix should be the obvious choice as it's 2 x DR if you get Rev.B.

 

[R-T-B]

Anyone try 4 sticks of dual for 8 ranks total?

I'm running this right now due to ram requirements. My 64GB kit is actually Samsung C-Die (thought it was b-die, is not) so not a good straight comparison to high end kits, but I can do DDR4-3200 no prob and from there to 3600 is like a 1% benchable difference so... might be worth it with a good kit and some luck? Dunno.

 

[GorbazTheDragon]

ya seems Ryzen specifically like 4 ranks total. so either 4 sticks of single or 2 sticks of dual.

Basically every modern (at least to the beginning of DDR3) platform wants 2 ranks per channel because of interleaving.

Although it depends on the platform and motherboards, usually 1 2R (dual rank) DIMM per channel is better than 2 1R DIMMs per channel, this is just down to the electrical properties of using 2 DIMMs being less favourable.

Anyone try 4 sticks of dual for 8 ranks total?

Avoid 2x 2R DIMMs per channel on all platforms, especially DDR4. You get very little gains from interleaving more than 2 ranks and the memory controller load and electrical properties are far worse so you end up losing a lot of performance due to lower frequency or worse timings.

I'd avoid talking about "total ranks" because different platforms have different numbers of channels. With memory ranks the important stuff is what the configuration within each channel is, and then you want to set up every other channel on your platform with that same configuration.

 

[The red spirit]

Dual rank has always been faster, it just depends on platform how much. Here's the difference:

Zen 3 - not much of difference in total performance, but for memory alone that's quite big impact.

General analysis - makes overall small difference, dual rank is faster at same clock speed and same timings, but single rank is seemingly more tunable leading to better performance.

General analysis - makes a tiny difference, but not always, even smaller difference.

What is memory rank

The concept of memory rank applies to all memory module form factors, though in general it tends to matter primarily on server platforms, due to the larger amounts of memory they manage.

www.crucial.com

Crucial says that more ranks are like more RAM sticks, so I guess each rank has access to CPU, thus more ranks may mean potentially more timely access to data.

Single Rank Memory vs. Dual Rank Memory (vs Quad Rank Memory) - OEMPCWorld

Single Rank Memory can be memory with chips on only one side of the memory module (stick of memory) or chips on both sides of the module as long as the chips are in one rank that is accessed while writing to or reading from the memory. Dual Rank Memory is basically like having two ... Single...

www.oempcworld.com

This website says that you get more bits to work with.

AMD Ryzen RAM scaling - performance effect in games (Page 6)

The impact of memory timings and frequency on AMD Ryzen 3000 systems in games has been a topic of discussion. In this artilcle we'll zoom in on specifically that. See, AMD made a change in 3rd gener...

www.guru3d.com

Guru3D noticed some performance gains from dual rank RAM

DIMMs: Single vs. Double vs. Quad Rank

What difference does the 'Rank' of DIMMs make to server memory? For example, when looking at server configurations I see the following being offered for the same server: 2GB (1x2GB) Single Rank PC3-

serverfault.com

Server forums says that it depends which is better

Memory rank - Wikipedia

en.wikipedia.org

Wikipedia has a great article about that, unless you overclock, more ranks are better, due to increased open pages and ability to access ranks independently.

I guess that's all.

In reality, it really doesn't matter much. Many manufacturers don't even specify how many ranks their stuff has and even same model RAM can have variating ranks.

 

[GorbazTheDragon]

rank is seemingly more tunable leading to better performance.

Well tuned dual rank b die beats well tuned single rank b die in just about anything that isn't absurdly latency sensitive like superpi... Games almost universally gain more from rank interleaving than they do from the frequency (and small timing) advantages you get from single rank.

Also on Ryzen you are capped at 4000 or so with frequency, at those speeds on modern boards the timing gains are next to nothing for single rank...

But as you say it's relatively small at the end of the day, and it's basically irrelevant when you are GPU bottlenecked... End user needs to evaluate whether it is worth pursuing or not.

 

[The red spirit]

But as you say it's relatively small at the end of the day, and it's basically irrelevant when you are GPU bottlenecked... End user needs to evaluate whether it is worth pursuing or not.

It's not that can pursue that either. In my country no shop even specifies how many ranks memory has. Many manufacturers don't say that either (like Corsair, Patriot, Team Group). It's one of those things that you really don't know until you get. Some people mentioned that you can look under heat spreader to see if both sides have chips, but that's not great strategy as some RAM can be dual rank and have all chips on one side (and probably vice versa). Maybe for server buyers, more data is given, but generally, manufacturers don't say how many ranks their RAM has. Even worse some brands don't even specify number of ranks on modules either (like Corsair). So you need some software like AIDA64 to actually know how many ranks memory has. So there's a lot of pain for small gains.

 

[GorbazTheDragon]

In my country no shop even specifies how many ranks memory has. Many manufacturers don't say that either (like Corsair, Patriot, Team Group).

The only manufacturer that specifies whether kits are dual or single rank on XMP kits is Kingston, everyone else does not do it for XMP kits (JEDEC memory basically always specifies it). Irrespective of that, b-die bin 16GB sticks are always dual rank because there is no IC that can match the primary timings (there is an exception in that crucial does have some high bin 16gb sticks that would appear to be b-die from the XMP timings but are actually micron 16gbit rev b so are single rank).

IMO if you are actually interested in the performance offered by dual rank you should automatically fall into the category of people for whom the performance offered by b-die is also interesting. So if you don't want b-die you shouldn't bother with dual rank either (unless ur looking to collect something specific)...

 

[The red spirit]

The only manufacturer that specifies whether kits are dual or single rank on XMP kits is Kingston, everyone else does not do it for XMP kits (JEDEC memory basically always specifies it).

That's not entirely true. Crucial sort of does that too, but they are describing that in more technical way:

Crucial Gaming products | High-performance gaming memory and storage

From hard-core gamers to casual players, we have the gaming products you need for the gaming experience you crave. Crucial's high performance gaming memory and storage fuels legendary gaming experiences.

www.crucial.com

They describe it as 2048Megx64. 2GB in 64 bits, so you get total of 16*64 and you end up at 1024 bits per stick. I'm pretty sure that can determine rank count from that somehow. And more than that, you know actual density and data width of cheap memory chip on stick, which may or may not be useful.

Irrespective of that, b-die bin 16GB sticks are always dual rank because there is no IC that can match the primary timings (there is an exception in that crucial does have some high bin 16gb sticks that would appear to be b-die from the XMP timings but are actually micron 16gbit rev b so are single rank).

IMO if you are actually interested in the performance offered by dual rank you should automatically fall into the category of people for whom the performance offered by b-die is also interesting.

Not at all. I still don't get the obsession with those B-Dies. People talk about them, but I still haven't bothered to check why. It likely only matters for overclockers anyway. And I'm not sure if I like overclocking. I both like it and dislike it at the same time.

So if you don't want b-die you shouldn't bother with dual rank either (unless ur looking to collect something specific)...

I'm not here to buy RAM.

 

[Solid State Soul ( SSS )]

Dual rank has always been faster, it just depends on platform how much. Here's the difference:

Zen 3 - not much of difference in total performance, but for memory alone that's quite big impact.

General analysis - makes overall small difference, dual rank is faster at same clock speed and same timings, but single rank is seemingly more tunable leading to better performance.

General analysis - makes a tiny difference, but not always, even smaller difference.

What is memory rank

The concept of memory rank applies to all memory module form factors, though in general it tends to matter primarily on server platforms, due to the larger amounts of memory they manage.

www.crucial.com

Crucial says that more ranks are like more RAM sticks, so I guess each rank has access to CPU, thus more ranks may mean potentially more timely access to data.

Single Rank Memory vs. Dual Rank Memory (vs Quad Rank Memory) - OEMPCWorld

Single Rank Memory can be memory with chips on only one side of the memory module (stick of memory) or chips on both sides of the module as long as the chips are in one rank that is accessed while writing to or reading from the memory. Dual Rank Memory is basically like having two ... Single...

www.oempcworld.com

This website says that you get more bits to work with.

AMD Ryzen RAM scaling - performance effect in games (Page 6)

The impact of memory timings and frequency on AMD Ryzen 3000 systems in games has been a topic of discussion. In this artilcle we'll zoom in on specifically that. See, AMD made a change in 3rd gener...

www.guru3d.com

Guru3D noticed some performance gains from dual rank RAM

DIMMs: Single vs. Double vs. Quad Rank

What difference does the 'Rank' of DIMMs make to server memory? For example, when looking at server configurations I see the following being offered for the same server: 2GB (1x2GB) Single Rank PC3-

serverfault.com

Server forums says that it depends which is better

Memory rank - Wikipedia

en.wikipedia.org

Wikipedia has a great article about that, unless you overclock, more ranks are better, due to increased open pages and ability to access ranks independently.

I guess that's all.

In reality, it really doesn't matter much. Many manufacturers don't even specify how many ranks their stuff has and even same model RAM can have variating ranks.

wow, you made a lot of efforts to gather as much information for a very informative answer, thank you very much ♥

 

[freeagent]

And I'm not sure if I like overclocking

Its not for everyone, and not everyone can do it, so don't feel bad. Its a hobby within the hobby.

 

[Solid State Soul ( SSS )]

Its not for everyone, and not everyone can do it, so don't feel bad. Its a hobby within the hobby.

The thing about overclocking is, in the old days it started as a hobby, but then companies started to put it front and center in their marketing materials for many years that even first time builders think its bad to build a non overclock able system which is not true, overclocking is always going out of spec, and you always lose a layer of stability when you do so, i personal find the hassles of overclocking for such small gains is not worth it, especially with the scummy tactics the overclocking marketing has gone to where, vendors will enable multi core enhancement on stock bios to sneakily overclock you processor, leading to users question high power draw and temps at 'stock" cogh cogh Asus cogh

i think a small bit of memory overclocking is fine, like if your platform supports 2133mhz DDR4, then buying a 2400mhz and enabling it trough XMP overclocking is ok, other than that i only buy H and B boards with non K processors knowing happily o can plug it and play on it from the get go

 

[freeagent]

The thing about overclocking is

I totally agree with you. I used to find it very satisfying, now its boring And by "now" I mean since X58 died, that was the last hurrah. Overclocking has become so mainstream these days, its almost sickening. But, that is what has become.. I almost bought a prebuilt.. back to my roots

I was into software before I got into hardware lol..

Also with todays pricing it is hard to want to support the industry. Manufacturers and customers have lost their way.. or maybe its just me getting old haha. Either way, its not what it used to be, and its getting harder for me to want to support them,

 

[GorbazTheDragon]

Crucial sort of does that too, but they are describing that in more technical way:

Crucial does not do it reliably, those 2x16 kits initially used dual rank rev E and later switched to single rank rev B, but always had single rank in the spec sheets. You can still occasionally run into the dual rank variants in stores...

They describe it as 2048Megx64.

x64 just refers to the width of the whole stick (64 bits, standard DDR4 channel width). 2048M refers to the size of each chip as you point out, so this module would have 8 chips to make 16GB, in general for XMP kits you can assume from that it runs in single rank mode since each IC is normally run in x8 width. If you had dual rank this would mean you need 8x8 chips on each rank, and as such 16 in total. There are some caveats here with running x4 and x16 width chips, but those are generally nonfactors with these XMP kits.

People talk about them, but I still haven't bothered to check why. It likely only matters for overclockers anyway.

Beyond overclockers who are just looking for better rankings on hwbot I would say the biggest practical benefits can be had by (competitive) gamers playing CPU limited titles: Warzone, WoW, and Overwatch are good examples among others. These games can still benefit greatly in smoothness by using a well configured system, part of which is running well tuned memory such as dual rank b die.

In general as has been reiterated throughout this thread the performance advantages are relatively small and not everything benefits from it, but these advantages add up (in the case of some games, RAM alone can net you 20-30% performance when going from 3200 XMP to a well tuned set of dual rank b-die).

m not here to buy RAM.

It's a general statement for hypothetical RAM buyer.

core enhancement on stock bios to sneakily overclock you processor

I mean the reason for this is entirely down to certain sites benchmarking motherboards just by out of box performance with a CPU... Scummy tactic I agree but it's just about them wanting the motherboard perform the fastest possible out the box... The funny thing is also that based on Intel's spec it isn't even overclocking so it's still running in warranty when doing that.

i think a small bit of memory overclocking is fine, like if your platform supports 2133mhz DDR4, then buying a 2400mhz and enabling it trough XMP overclocking is ok, other than that i only buy H and B boards with non K processors knowing happily o can plug it and play on it from the get go

Everyone is looking for different requirements, for a productivity workstation or home server I would generally not recommend going over JEDEC and would say to consider ECC. For most gamers I would say XMP is fine because most people don't play CPU limited, but there are a subset of people looking for the best fps and smoothest experience, and those can still benefit quite a lot from overclocking memory.

Of course it is still an involved process, so for some people it's just not worth it. But a well configured overclock should always be stable.

 

[Chomiq]

Speaking of ranks:

It is tempting, even given the high odds of it being single rank Rev B kit.

Same kit goes for €220 over here.