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Double height DDR4 offers twice the capacity but a fraction of the compatibility

By Shawn Knight · 21 replies
Jan 25, 2019
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  1. Double height DDR4 modules started making noise last year, promising benefits to both small form factor builders and those with the need for more than 64GB of total memory (assuming your platform of choice supports it).

    True to their name, these modules offer double the capacity of a standard DDR4 module – so up to 32GB per stick. To make room for the additional ICs, however, the height of the modules has been increased. If you’re concerned about CPU cooler clearance, it’s something you’ll want to consider beforehand.

    AnandTech recently hosted two of these new kits on its test bench – the 2x32GB G.Skill TridentZ RGB DC DDR4-3200 CL14 (1.35V) and the 2x32GB ZADAK Shield RGB DC DDR4-3200 CL14 (1.35V) – using an ASUS ROG Strix Z390-I Gaming (BIOS Version 1003) motherboard and an Intel Core i7-8700K, comparing them to a trio of 2x16GB kits.

    Notably, only three motherboards are currently validated for use with double height memory: the aforementioned Strix board, the ASUS ROG Maximus XI Apex and the ASUS ROG Maximus XI Gene.

    As for the technology that makes double height RAM possible, AnandTech does a great job in explaining it:

    Using 8 Gb Samsung B-die chips, a normal 16 GB module would have 16 of them to make it up to capacity. For these modules, to reach 32 GB per module, there are 32 x 8 gigabit chips. These are split into two ranks of sixteen chips, and act as if there are two memory modules on the same channel. Modern mainstream processors support 'two DIMMs per channel', meaning two memory modules per channel, which is why we see motherboards for dual channel processors have a total of four slots. By putting two modules onto one PCB, only one slot is needed to hit 'two DIMMs per channel'.

    In testing, AnandTech found that performance was consistent across both kits and on par with G.Skill's TridentZ RGB DDR4-3200 standard 2x16 GB kit. Surprisingly enough, the double height design with its longer traces from the ICs was even beneficial in some scenarios.

    It would seem that the only real benefit to going this route is if you absolutely need the additional capacity. Even then, only a few boards and kits are available and you’re going to pay about the same price of what the equivalent capacity would cost in “standard” sized sticks. ZADAK, for example, said its baseline DDR4-2666 CL16 kit will start at $799.

    Lead image courtesy AnandTech

    Permalink to story.

     
  2. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,401   +5,021

    If it becomes a standard, I would think about taking a risk.
     
  3. Cycloid Torus

    Cycloid Torus Stone age computing - click on the rock below.. Posts: 4,067   +1,190

    Man, that's a lot of memories!! If it is established as a standard for at least a year, I might catch up with it then.
     
  4. captaincranky

    captaincranky TechSpot Addict Posts: 14,972   +4,009

    Call me a Luddite, but since these kill one socket of a memory channel, wouldn't it just be cheaper to buy 4 X 16 GB :confused:

    If you could use all four RAM sockets, you would have 128 GB total, but you can't, so what's the point? If anything other than to foul your cooler with them?

    Of course if you're that far into it, you likely wouldn't be using an air cooler, but still.
     
  5. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,401   +5,021

    Lay the memory slots down the way laptops slots are. For the life of me, I can't understand why this is not common place.
     
    JaredTheDragon likes this.
  6. Vulcanproject

    Vulcanproject TS Evangelist Posts: 740   +1,071

    Heat for one. High end modules can get very warm indeed, stood up with air circulation is beneficial especially for servers. No big deal for SODIMMs laid against each other when it's low voltage and lower speed.
     
  7. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,254   +907

    Most PC cases should have no problem with these.

    I have an AREA 51 Core i9 Triad with 32GB of standard DDR4 and I know I won't have an issue with that height.
     
  8. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,254   +907


    Heat release is the main reason. Desktops are way hotter than laptops. Vulcan answered it before me.
     
  9. TheBigFatClown

    TheBigFatClown TS Evangelist Posts: 744   +274

    Let me just say this. Pass and Fail!
     
  10. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,401   +5,021

    I'm willing to bet the majority are not.
     
  11. captaincranky

    captaincranky TechSpot Addict Posts: 14,972   +4,009

    FIXED! er, maybe? :confused:
     
  12. i3kingwizardop

    i3kingwizardop TS Booster Posts: 42   +17

    Normal people don't need 32gb per slot, is the problem. Maybe servers or Linus, perhaps...
     
  13. seeprime

    seeprime TS Guru Posts: 382   +410

    The purpose of these sticks seems to be to allow miniITX boards to act like they have four slots, which will double the maximum memory from 32 to 64GB.
     
  14. captaincranky

    captaincranky TechSpot Addict Posts: 14,972   +4,009

    Oh. :facepalm: Being the cynical curmudgeon I am, I thought they were so you could intimidate your potential gaming opponents by declaring, "oh yeah m***** f******, back off, 'cause I gotz me 128 GB of RAM in this here box"...:eek:
     
  15. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,254   +907


    Are you kidding?

    Higher voltages for one.

    More components with their own heat release issues for two.
     
  16. Uncle Al

    Uncle Al TS Evangelist Posts: 5,397   +3,782

    Might be ahead of it's time but compatible motherboards will catch up and I'm sure that there will be a few new cooling options for them as time rolls on, but I'm really wondering how bumping up from 64 to 128 mb or ram is going to make that much a difference in performance .....
     
  17. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,254   +907


    GB you mean.. Not MB.

    for people with workstations who actually need 128GB of RAM, it will be essential.

    32GB sticks are also about reducing packaging. This way a computer can be smaller with a smaller motherboard and still pack 32GB or 64GB of RAM.

    Take a look at your average workstation. They try to make them smaller.
     
  18. captaincranky

    captaincranky TechSpot Addict Posts: 14,972   +4,009

    Perhaps so, but for home self proclaimed "gaming power users", perhaps not so necessary.
    And yet, I don't think they're going to redesign all the server racks to accommodate this novelty. Besides, this iteration appears not to be ECC.

    Oh well, as it's already nice and tacky with RGB flashing lights, I'm sure it will find its niche.
     
  19. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,401   +5,021

    I'll go along with the heat issues but that is only for higher frequencies, which in turn requires more power. But higher voltage is BS. Neither socket design would be limited to less voltage than the other. If either socket design runs on less voltage, it would be the module design limiting power usage. In which case desktop modules could also be designed the same way. In essence that is precisely what DDR3L and DDR3U are. The low profile sockets could still run at higher voltages. It is as said previously a heat issue from said voltages. However the majority do not need such power requirements in their usage of memory. Heck they do most of their processing from a phone anyway.

    I will concede from my statement. I do wish there was more desktop boards available that used laptop memory. What I'm asking for does exist, just not for standard modules (AFAIK). Therefor picking modules and CPU cooler can be tricky.
     
  20. Axiarus

    Axiarus TS Evangelist Posts: 460   +268

    Could easily get around this with an AIO CPU cooler.
     
  21. Axiarus

    Axiarus TS Evangelist Posts: 460   +268

    There is a lot more space to go away from the motherboard into the case than across it.
     
  22. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 11,401   +5,021

    That would only be true, if the modules wasn't within an inch of the CPU. They put these slot on Notebooks. You must be telling me a Notebook has more room than a Desktop. They seem to have found room for an M.2 slot. On many boards even two or more M.2 slots. Your point has officially been myth busted.

    I think we need to stick with heat issue, which the majority do not encounter.
     

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