Double Height DDR4: 32GB Modules from G.Skill and ZADAK Reviewed
by Ian Cutress & Gavin Bonshor on January 23, 2019 9:00 AM ESTDC RAM Overclocking Performance
Memory overclocking can usually be approached in multiple ways. DDR4 Memory kits come supplied with integrated 'XMP 2.0' profiles which means users don't really need to do anything other than clicking a button inside the BIOS in order to achieve the memory kit's rated performance. However manual tweaking is required to go further.
The fine art of memory overclocking is a long and windy road for minimal performance gains. It almost becomes a performance piece, needing a seasoned expert to get the best out of it. However most users can at least adjust the frequency the primary latencies. The frequency which can be changed via the strap/multiplier and through the base clock generator is more common, while the timings are usually done as the second step once a stable frequency has been found.
Both of the memory modules we have are equipped with Samsung B-die chips. These chips are often considered some of the best overclocking parts, however there is some natural speculation as to how they will perform in this double height form factor.
To measure the overclockability of the DC RAM, the stock performance with the XMP 2.0 profile applied on both the G.Skill TridentZ RGB DC and ZADAK Shield RGB DC 2x32 GB kits are used as a baseline. We exokired both pushing the frequency as high as could be managed, and then with latencies as tight as much as possible. As WinRAR 5.40 proved one of the more memory sensitive benchmarks in our list, we used this to highlight the performance, if any, from the DC memory.
Highest 24/7 Frequency at 16-16-16: DDR4-3500
The maximum overclock we managed to achieve with a voltage of 1.5 V on the DRAM for each kit is as follows:
G.Skill TridentZ RGB DC - DDR4-3500 16-16-16-38
ZADAK Shield RGB DC - DDR4-3500 16-16-16-38
We were unable to go beyond DDR4-3500 even with 18-18-18 sub-timings.
Best 24/7 Latencies at DDR4-3200: 12-12-12
The tightest timings while keeping the frequency at their XMP rating of DDR4-3200 with a voltage of 1.5 V on the DRAM is as follows:
G.Skill TridentZ RGB DC - DDR4-3200 12-12-12-32
ZADAK Shield RGB DC - DDR4-3200 12-12-12-28
Overall Reasonable Overclock: DDR4-3400 14-14-14 at 1.5 V
The highest achieved DRAM frequency achieved with tighter timing adjustments with a voltage of 1.5 V on each kit is as follows:
G.Skill TridentZ RGB DC - DDR4-3400 14-14-14-34
ZADAK Shield RGB DC - DDR4-3400 14-14-14-32
As our maximum achieved overclocks show, there isn't much additional headroom available to push the dual capacity DRAM much further than the XMP 2.0 profiles already allow. Both the G.Skill and ZADAK kits allowed us to overclock up to DDR4-3500 with 16-16-16-38 at 1.5 V. Any attempt to go past DDR4-3500 would result in failed POST even with timings slackened as loose as up to CL18. When it came to tightening up the latency timings, both kits experienced similar timings with the G.Skill TridentZ RGB DC allowing for DDR4-3200 14-14-14-32, with the ZADAK Shield RGB DC giving slightly tighter tRAS timing with DDR4-3200 14-14-14-28.
Users thinking that overclocking will be as prosperous as others have achieved on DRAM in 1Rx8 or 2Rx8 featuring Samsung B-die ICs aren't going to be as happy with the headroom on these modules. The headroom available is limited and the performance displayed in our WinRAR test was mirrored here. On the G.Skill TridentZ RGB DC kit a total of 0.9 seconds with a mixture of frequency and timing adjustments equalling DDR4-3400 14-14-14-34 applied. Overclocking the ZADAK Shield RGB DC memory to DDR4-3400 14-14-14-32 proved the best settings that we tried with a reduction of 1.3 seconds. Answering any questions about the overclocking ability of the memory, our testing with the samples we received proved dreary in comparison to what's usually expected from Samsung B-die ICs.
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Alim345 - Wednesday, January 23, 2019 - link
It’s not clear whether it is possible to use four sticks. Probably it is not since those sticks replicate what should happen in motherboard.Targon - Thursday, January 24, 2019 - link
Much of that would be a function of the chipset/BIOS and the memory controller which is on the CPU these days. These double height modules can't directly talk to the memory controller as if they are two modules, because the memory slots themselves and how they talk to the chipset/memory controller/CPU are not different.That is why I wanted to see at least an attempt to get these to work with a socket AM4 system and see how they show up. Going from 1T or 2T to 2T or 4T for the memory is probably the issue, and if the chipset would even allow it. Asking Asus if they have plans to allow DDR4 to run with a 4T command rate on more boards would be worth the call.
nevcairiel - Wednesday, January 23, 2019 - link
Since one of those DIMMs basically acts like two DIMMs, you probably cannot use two of them on the same channel, since that would require supporting 4 DIMMs on the same channel.Targon - Thursday, January 24, 2019 - link
I don't think it works that way. Yes, internally each one is working as if it was two, but how the module talks to the BIOS/chipset/processor is the big question. Does the BIOS need to support a 4T command rate on the memory for these to work, and if so, that explains why support is limited.Bp_968 - Thursday, January 24, 2019 - link
He explained in the article that the way memory channels are handled that the traces are daisy chained or combined. These dimms act as 2 dimms slapped onto one card and won't work stacked 2 too a channel (because then you'd have 4 dimms on a channel).Above and beyond that you also have the fact that now 32GB modules exist which render these far less useful. There are very very few scenarios where you'd want 128GB of ram and not want it to be ECC RAM. Any sort of server and many workstation tasks I'd much prefer to use ECC ram instead.
yuhong - Wednesday, January 23, 2019 - link
Even Intel don't usually update ARK or the datasheet.alpha754293 - Wednesday, January 23, 2019 - link
Maybe I'm missinng something here - but I don't understand why people just don't get 32 GB DDR4-2666 ECC Registered DIMMS like this one (https://www.newegg.com/Product/Product.aspx?Item=N... and be done with it?It's going to run about the same price and they can just overclock it.
Wixman666 - Wednesday, January 23, 2019 - link
Because most boards don't run ECC memory. These are a niche product to get 64GB on boards that only have 2 slots. Lots of memory doesn't overclock well. You're making assumptions with your statement that are completely off base.CheapSushi - Thursday, January 24, 2019 - link
Does that mean ECC RAM will NOT WORK AT ALL or just the ECC portion, soft error correcting, won't work but it'll show up like regular RAM?alpha754293 - Thursday, January 24, 2019 - link
I've used ECC memory on consumer grade boards. All that happens is that the ECC part of the ECC, Registered RAM gets disabled and the rest of the DIMM module functions like a UDIMM instead of a RDIMM."You're making assumptions with your statement that are completely off base."
Yes! Which is why I literally said: "Maybe I'm missinng something here - but I don't understand why people just don't get 32 GB DDR4-2666 ECC Registered DIMMS like this one (https://www.newegg.com/Product/Product.aspx?Item=N... and be done with it?"
Lots of memory don't overclock well is just a broad and generic statement that can also be applied to these modules as well.
The fact of the matter is that DDR4-3000 and DDR4-3200 modules ARE overclocked by default anyways because those speeds aren't part of the JEDEC JESD79-4 spec (p.163).
Here is a 32 GB module from Micron Technology, DDR4-3200, ECC Registered: https://www.ebay.com/itm/Micron-MTA36ASF4G72PZ-3G2...
The point being that a) they exist already and b) you should be able to disable the ECC, registered capabilities of these DIMMs. (I've never had a consumer grade board that didn't know how to ignore the ECC registered capabilities of RDIMMs.)
In other words, you can already do this with existing modules that you can buy, at those speeds, "second" hand (which tells you a little bit about the maturity of the tech).