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[Solved] Zen 2 - DDR4 will it do Dual Rank?  

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Remklep
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June 14, 2019 06:03  

So I'm planning out my Zen 2 build.

The Zen and Zen+ CPUs have had problems with dual rank memory by not clocking the DDR4 as high as the same size single rank DDR4 sticks.
I'm thinking about getting one of the higher end Aorus motherboards, they have the DDR4 sockets connected to the CPU-socket in a daisy chain configuration (no more T Topology thank god, oh wait there is no god... Thank some imaginary character).
This means for better performance I only want one bank of each of the two available memory controllers fitted with one DDR4 stick.
Furthermore as the infinity fabric will clock at half the speed of the DDR4, if the DDR4 is running faster then 3733MHz, I want to run the DDR4 at 3733MHz.

As I want the new build to have 32GB, I have been looking for 32GB 3733MHz (or better) single rank 2 stick kits, but haven't found any.

If the new memory controller of Zen 2 has no more problems with dual rank DDR4 sticks, then I just wasted 10 minutes.
I hope I wasted my time...


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muziqaz
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June 14, 2019 08:42  

With the leaks of RAM clocking to 5+GHz on Zen 2, I think memory compatibility issues are the thing of the past.

Asrock x570Taichi/3900x/Radeon7/16Gb3600Mhz/Samsung970Evo+Intel750Series/SamsungHDR-Freesync2
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Ype
 Ype
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June 14, 2019 11:38  

Remklep, we won't know for sure until the reviews but from what I've seen:

Low latency ram at 3200 gives almost the same reduction in latency as 3733 on ZEN2 according to AMD.

Dual rank sticks will give you a slight boots in performance when ran at the same speed/timings as single rank sticks due to the ability to refresh one rank while having reading/writing operations on the other.

Populating 4 slots will give you dual rank like performance as you now have the same advantage, it can read from one stick while refreshing the other on the same memory channel. There is no way for me to tell for certain if two single rank sticks in one channel will work better then one dual rank module due to the daisy chain topology of the motherboard.

If I would want to go for two dual rank modules I would take a motherboard with only 2 ram slots. This way I wouldn't have to worry about the signal integrity loss from daisy changing. Even when only one slot per channel is populated the other slot can still pick up some interference, the reason why highly priced boards for overclocking sometimes have only two slots.

I hope this helps,
Ype

 

Edit: Keep in mind that my knowledge on this subject is quite dated.

This post was modified 1 year ago 2 times by Ype

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Rand Walker
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June 14, 2019 16:07  

Now I have to re-watch Buildzoid's video on motherboard memory layouts.

https://www.youtube.com/watch?v=3vQwGGbW1AE


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Remklep
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June 14, 2019 16:34  
Posted by: Ype

Dual rank sticks will give you a slight boots in performance when ran at the same speed/timings as single rank sticks due to the ability to refresh one rank while having reading/writing operations on the other.

Ype,

Thanks for the reminder of  the memory refresh of the rank that is not in use.

As I am going to wait until September for the 3950X, I'm sure there will be plenty reviews and benchmarks available online to make up my mind regarding single or dual ranks.

If dual rank is no problem on Zen 2, I'll get a 32GB kit consisting of 2 16GB 3733 dual rank sticks.

 


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thehumangerm
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June 15, 2019 07:42  

Ryzen 3000 is having no problems reaching speeds of 4000 Mhz according to board partners. The theoretical limit of the chip is 5000Mhz but those speeds are more of a pipe dream without horrid CAS latency and as mentioned above you get slower infinity fabric speed doing so anyway. So this only makes sense for people really needing the increased bandwidth which is not in the gaming market. AMD has said that the sweet spot for Ram performance on Ryzen 3000 is 3600. Your best bet is getting a 3600 kit with good CAS latency and calling it good. anything above 3600 drastically increases the RAM cost and provides virtually zero performance gain. Even the gain of 3200 to 3600 is not really meaningful considering the $50-100 dollar price difference on a 16 gig kit is better spent on another part upgrade.

As far as dual channel support there are no known issues. There will be no quad channel support however. On Zen 2 there is also no issue with dual channel.

This post was modified 1 year ago 2 times by thehumangerm

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Remklep
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June 16, 2019 02:08  
Posted by: thehumangerm

As far as dual channel support there are no known issues. There will be no quad channel support however. On Zen 2 there is also no issue with dual channel.

Hi thehumangerm,

Just to make sure, I’m not talking about single or dual channel, we already know Zen 2 has a dual channel memory controller.

I was wondering if the dual channel memory controller could have problems with dual rank memory sticks like in the previous iterations of Zen.


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thehumangerm
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June 16, 2019 03:03  
Posted by: Remklep
Posted by: thehumangerm

As far as dual channel support there are no known issues. There will be no quad channel support however. On Zen 2 there is also no issue with dual channel.

Hi thehumangerm,

Just to make sure, I’m not talking about single or dual channel, we already know Zen 2 has a dual channel memory controller.

I was wondering if the dual channel memory controller could have problems with dual rank memory sticks like in the previous iterations of Zen.

There has been no official talk on this but what I can tell you is that we are getting a new memory control that is now on the IO die not the chiplet and dual rank support was a known issue. Also with samsung discontinuing b die memory and board partners saying they have been seeing good memory support I do not see it being an issue.


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Remklep
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July 30, 2019 17:06  

Answer provided by Buildzoid:

https://www.youtube.com/watch?v=nugwAOvijHQ

TLDR:
Zen 2 loves DualRank 3800 MHz DDR4 when running Uclk and Fclk at the same speed.


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muziqaz
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July 30, 2019 17:36  
Posted by: Remklep

Answer provided by Buildzoid:

https://www.youtube.com/watch?v=nugwAOvijHQ

TLDR:
Zen 2 loves DualRank 3800 MHz DDR4 when running Uclk and Fclk at the same speed.

Mine is b die single rank 4000mhz dimms

So I'm half way there. Now UCLK and FCLK, where do I find these in Asrock BIOS. FCLK is Infinity fabric clock, that's fine, I think I saw that. UCLK.

Asrock x570Taichi/3900x/Radeon7/16Gb3600Mhz/Samsung970Evo+Intel750Series/SamsungHDR-Freesync2
Hero7/2700x/Vega64LE/8Gb2933Mhz/DellUltraSharp4K
Blue eyed WRX STI


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Luke
 Luke
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July 31, 2019 03:06  

I played with my B Die yesterday.  I was apprehensive about bumping VDRAM up to 1.5V, but the temperatures are rock solid. 

I settled on 1900/1900 with 14.14.14.34.  What voltage are you guys using with B Die?


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muziqaz
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July 31, 2019 03:27  

I cry when I'm using anything above 1.4v, but that's just me. And here you guys thinking of 1.5vs. by the way what's the temp limit for DIMMS? I have NZXT sensor tucked inside the heatsink of one of my memory sticks, I know it's not comparable to actual internal sensors but at least it gives me quick and dirty reading of the atmosphere around memory kit 😀 it idles at 30c and loads bring it to 40c. But then again I haven't even started fiddling with my memory so it's at very conservative settings

Asrock x570Taichi/3900x/Radeon7/16Gb3600Mhz/Samsung970Evo+Intel750Series/SamsungHDR-Freesync2
Hero7/2700x/Vega64LE/8Gb2933Mhz/DellUltraSharp4K
Blue eyed WRX STI


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Ype
 Ype
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July 31, 2019 05:05  

@lukedotde
Looking good buddy!
I am running mine at 14/15/15/30/45 right now, manual sub timings, 1800/1800.
1.1V on the SOC and 1.46V on the RAM.

Edit: the moment I went above 1800 for the FCLK my PC didn't POST properly.
When that happens I am back at 2133Mhz on the ram.
Going directly to the last working settings won't work, I have to up the ram and FCLK speed in increments to get back to 1800/1800.

When a new BIOS comes out that fixes my trip down reboot lane I'll see how far I can push the FCLK and how much I can tighten the RAM.

@muziqaz
Adding a second single rank kit to your setup will get you up to dual rank per channel.
I did a quick write-up on this behavior in a previous post in this thread.
Just combine the same memory IC's and you'll be fine.

@lukedotde @muziqaz
As far as I know memory IC's have to be able to run 1.5V without issues according to JEDEC specifications.
Above that your mileage my vary.

As for max IC temperature, a quick look in the data sheet tells you that the max operation temperature is 95c.
In practice mine don't go over 50C while testing my memory with Prime95 and the RAM at 1.5V.

https://www.samsung.com/semiconductor/global.semi/file/resource/2017/11/8G_B_DDR4_Samsung_Spec_Rev2_1_Feb_17-0.pdf

This post was modified 12 months ago by Ype

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Luke
 Luke
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July 31, 2019 05:08  

As far as temperatures, I haven't seen my dimms exceed 37*C yet. I'm a little surprised because I don't have much air flow directed on them.


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Remklep
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July 31, 2019 05:25  
Posted by: muziqaz
Posted by: Remklep

Answer provided by Buildzoid:

https://www.youtube.com/watch?v=nugwAOvijHQ

TLDR:
Zen 2 loves DualRank 3800 MHz DDR4 when running Uclk and Fclk at the same speed.

Mine is b die single rank 4000mhz dimms

So I'm half way there. Now UCLK and FCLK, where do I find these in Asrock BIOS. FCLK is Infinity fabric clock, that's fine, I think I saw that. UCLK.

Uclk is the memory clock speed, so for DDR4 3800 it would be 1900MHz.


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