One of the interesting things to come out of the news in recent weeks is the march to double capacity memory. In today’s market, memory modules for consumer grade computers have a maximum of 16GB per module. This is unbuffered memory, and the standard for home computers and laptops. However recently there have been two major announcements causing that number to double from 16GB to 32GB: Samsung has developed double capacity ICs to drive up to 32GB per module with the same number of chips, but also a couple of DRAM vendors have found a way to put two times as many ICs on a 16GB module to make it up to 32GB. Both G.Skill and ZADAK fall into that latter category, and now we have both of these kits in the lab for review.

Double Capacity DRAM

With memory modules using double the number of chips, the easiest way to enable this is by having taller PCBs. This is exactly what we get.

Here we have G.Skill’s new TridentZ DC RGB memory and a regular module of TridentZ RGB in a motherboard. G.Skill stated that their memory is essentially two UDIMM modules on one PCB, with double chips, double ePROM, and power management. The technical parts involve the pin definitions, the tracing layout, and fine tuning.

This obviously has implications for coolers, with both companies recommending liquid coolers be used to avoid issues with fans not sitting correctly.

The G.Skill TridentZ DC RGB kit is a 2x32GB design running at DDR4-3200 14-14-14, which is a fairly aggressive timing. Price is expected to be rather high.

The ZADAK kit, called ZADAK Shield DC DDR4, runs at similar specifications to the G.Skill kit: 2x32GB running at DDR4-3200 14-16-16. We were told that the price of this kit is going to be nearly USD$1000.

At present, only a trio of Z390 ASUS motherboards are qualified with both memory kits. These are the ASUS ROG Maximus XI Apex, the ROG Maximus XI Gene, and the ASUS Strix Z390-I Gaming. We are awaiting one of these to arrive to begin testing.

At the moment we are looking into what benchmarks we can use to not only differentiate between the kits but also compare them to other memory. Just having double capacity is not enough – we intend to look into power and performance as well. Suggestions are more than welcome!

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  • Another IT Guy - Friday, November 09, 2018 - link

    About 13 years ago, I was assembling some Xeon servers we had purchased from IBM (think xSeries 365 or so) and bought some dual-rank RAM to fill them out. I don't recall the exact number but only a portion of the memory worked and IBM explained that their BIOS addressed the memory by addressable chip, and we had simply put more chips in the slots than they had available. It wasn't documented, and they worked with our memory rep to replace the (of course) non-refundable RAM. Probably not an issue for our desktops, but I would be concerned with higher memory counts like you'd find with people trying to build virtualization hosts. Reply
  • alacard - Friday, November 09, 2018 - link

    I have the same kit with 16GB modules: 64GB DDR4 3200@14-14-14 with a Row Refresh Cycle Time @ 560 with a command rate of 2T.

    5 Questions:

    1) What is the Row Refresh Cycle Time for this kit. (I may be a complete idiot here, but I suspect the tRFC is where RAM producers mask their latency in order to get better numbers in the big three Madison Avenue metrics [CL, tRCD, & tRP])
    2) What is the voltage.
    3) What is the latency and bandwidth compared to 4x16GB of the same amount of memory rated at these speeds.
    4) What is the latency and bandwidth @ 4x32GB for both samples.
    5) What is the command rate of the 32GB modules.
    Reply
  • kpb321 - Friday, November 09, 2018 - link

    I don't think 4x32 is possible with these. If you look up the supported MBs they are all limited to 2 slots with only 1 DPC.

    With the article saying "essentially two UDIMM modules on one PCB, with double chips, double ePROM" I take that to mean that these boards will see it as 1 DPC when one of these is installed. None of the consumer chips support more than 2 DPC so should not allow you to do 4X32 because it would see it as 4 DPC.
    Reply
  • kpb321 - Friday, November 09, 2018 - link

    **will see it as 2 DPC when one of these is installed Reply
  • yuhong - Friday, November 09, 2018 - link

    The 16Gbit DDR4 based DIMMs should also be easier to find this month. Reply
  • dwzl - Friday, November 09, 2018 - link

    How does one buy these? Reply
  • npz - Friday, November 09, 2018 - link

    > At present, only a trio of Z390 ASUS motherboards are qualified with both memory kits. These are the ASUS ROG Maximus XI Apex, the ROG Maximus XI Gene, and the ASUS Strix Z390-I Gaming

    With only slots on those boards and how the DIMMS are two-in-one I assume it'll only work for those boards and not with 4 DIMM slots fully populated, but that is something I'd really like tested and/or verified by Gskill and Asus or other mobo makers
    Reply
  • npz - Friday, November 09, 2018 - link

    edit: should be: "With only 2 slots on those boards ..." Reply
  • evilpaul666 - Saturday, November 10, 2018 - link

    It's a follow up to the Anandtech article dated 10/25/2018 titled, "Intel to Support 128GB of DDR4 on Core 9th Gen Desktop Processors", so presumably you'll be able to use 4x 32GB on some boards.

    I went with 4x 8GB when I put together my system ~2 years ago (back when prices weren't crazy stupid) and really wish I'd sprung for 64 GB.
    Reply
  • DanNeely - Sunday, November 11, 2018 - link

    That's almost certainly with normal 32GB DIMMs using the high capacity chips Samsung isn't selling to anyone else yet.

    You can only put two Dimm's worth of ram chips on a DDR* bus before you've got too many devices attached for the signal quality to remain in spec. These offbeat dimms are putting twice as many ram chips on a single dimm, meaning there's only electrical capacity for one/channel not two.

    High end servers get around the issue by using a buffer chip on each dimm, so only the single buffer is connected to the memory bus not all 8 or 9 (ECC) ram chips. There's no free lunch though, having to pass all commands and data through the buffer chip adds significantly to latency.
    Reply

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