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BadSweetums
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Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 11:25 am

My i5-3470 system has served me well; but I want bragging rights. So, I hope to spec a high-end Ryzen system that totally rocks and completely works. Rocks = it just does it, almost zero waiting. Completely works = nothing that just adds eyewash; like a Windows 98 system with one GB of system memory or adding unicorn stickers.

CPU: Ryzen 8-core 16 thread, would say 1800X, but might be unnecessary support of marketing based binning. (tested products marketed as 1800X, 1700 may be an 1800X without a sticker)

Motherboard: X370 chipset board featuring PCIe x4 M.2 socket for a 512MB boot drive, good support for 4-channel memory at higher speed and quicker timings; or, 2-ch memory might be as good as it gets.

System Memory: Where I see a swamp of marketing claims and limited proofs. Gigabyte's GA-AX370-Gaming 5 motherboard memory QVL shows 4-ch support at DDR4 2666 with several brands at 16-16-16-36 and 2-ch support at up to DDR4 3200 with one brand at 14-14-14-34

Graphics: Either carry on with my aging 650 ti Boost until the Vega boards arrive latter; or, add a placeholder until the dust settles. The Sapphire R9 Fury Nitro is appealing, but it is end of life.

I'm looking for informed analysis. I know the NDAs have not expired, so no one has actually built systems that they can talk about. But, will 2-ch interleaved memory vs 4-ch interleaved memory in a Ryzen system test differently than in an X99/i7-5820K system?

Gordon Mah Ung, an executive editor at PCWorld, opines that 4-ch memory only adds to SiSoft Sandra’s memory bandwidth test, 4-ch = 200% 2-ch. He bases that on comparing one i7-5820K processor in two different X99 motherboards with 16GB of total system memory in 2 and 4 DIMM slots. Productivity workware, zipping/unzipping, games and video encoding showed no meaningful difference, pretty much 99.999 vs 100 across both systems. http://www.pcworld.com/article/2982965/ ... mance.html

So, how many people think (or secretly know) that AMD has matched Intel's system memory performance; OR, has AMD gotten improved real world results from 4-ch memory and reversed the super socket seven debacle.

Super socket seven, SS7, was AMD holding onto socket seven while Intel introduced Slot One and the 440BX chipset that sealed their lock on world domination. I read a comparison of hard drive transfer speeds and that was the end of AMD for me until they gave up Slot A. I have fond memories of running a Celeron 366 as a Celeron 550. And, then a pair of them. (Yeah Bay Bee!!!)

Reversing the SS7 debacle would mean AMD's Ryzen gets a real performance boost from 4-ch memory bandwidth and Intel is only using it as a unicorn sticker.

Has anybody wasted time, money, tech subscriptions or whatever to analyze this geeky topic? Or, must I wait for someone to officially get their hands on the material necessary to replicate Mr Ung's experiment using AMD parts? AMD should be motivated. If Ryzen uses 4-ch memory better than Intel's chips.

Intel is certain to make sure that everyone knows Intel's AVX support is "better" than AMD's. At least that was my take away from early analyses of Ryzens kicking Intel booty overall but not being perfect.

So there it is. Is a Ryzen CPU and X370 chipset able to use 4-ch system memory effectively? Or, should I concentrate on faster memory for 2-ch?
 
DPete27
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 11:35 am

Ryzen actually has 4-ch memory controller? or is it 2x2ch like Intel's mainstream CPUs? Notice how true quad channel moboshave 8 RAM slots? All the X370 boards I've seen have 4 RAM slots total. I wouldn't advise filling all 4 off the bat with low capacity DIMMs. Most computers need a doubling of RAM during their useful lifetime.

You clearly have little need for GPU horsepower if you're still on a 650Ti. Wait for Vega.

[Edits]Cant type
Last edited by DPete27 on Thu Feb 23, 2017 11:41 am, edited 2 times in total.
Main: i5-3570K, ASRock Z77 Pro4-M, MSI RX480 8G, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, EVGA 550-G2, Silverstone PS07B
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 11:39 am

Summit Ridge Ryzen processors only have a dual-channel memory controller.
 
BadSweetums
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 11:58 am

Thanks for clearing that up, you made things a lot easier than I thought it would be.

I confess to being an advanced barbarian with limited interest in digging through the piles of boiler plate that sometimes unintentionally hide minor important details like "can this part make good use of 4-ch memory?"

Thanks again, you've made me a happy camper.
 
ronch
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 12:09 pm

It may concern some folks to know that 8-core Ryzen models only have 2 memory channels when the Intel parts they're competing against have 4. This is partially offset by support for higher DDR4 speeds. The 6900K, for example, officially supports DDR4-2400 while there's word on the street that Ryzen officially supports DDR4-3600. Faster memory is of course more expensive, generally speaking, but I reckon it's more than offset by cheaper boards that only support dual channel instead of quad. Still, 25% theoretical lower memory bandwidth is a concern, and that's not taking into account the fact that Intel can run with faster DDR4 sticks. We'll just have to wait and see how this story unfolds.
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BadSweetums
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 12:23 pm

I personally refuse to commit; but, the PCWorld article I cited in my original post showed no real world performance loss for an i7-5820K with 16 GBs of system memory installed as 2-ch (2 x 8GB) in a 2 DIMM slot mini-ITX X99 motherboard compared to the same CPU installed in a full-size Asus X99 Pro motherboard with 16 GBs of system memory installed as 4-ch (4 x 4GB).

So, Intel's 4-ch solution may be a unicorn sticker. Something for marketing to hype while the technicians shrug their shoulders and cash their paychecks.
 
defaultluser
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 12:41 pm

Intel 4-channel controller is overkill, designed to support the Xeons that are ALSO supported on that platform. Cause you know, 22 cores on a single memory controller :)

8-10 cores have been easy to feed with dual-channel since the introduction of DDR4. This is TWICE the bandwidth that LGA 1366 launched with a decade ago, and at the time that triple-channel controller was overkill for the parts.

Also, that amount of memory bandwidth only really gets used by Workstation-level or Server-level tasks, like 4k video editing, or in-memory database. Or a bandwidth hog like an integrated GPU :D

I GUARANTEE Coffee Lake will be dual-channel.
 
BadSweetums
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 12:58 pm

even as I suspectaltated. Engineering for marketing BS. Maybe when CPUs move to a wider memory bus. Intel's integrated GPUs still are like a candle burning dimly in a distant house on a foggy night.
 
DPete27
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Thu Feb 23, 2017 2:13 pm

ronch wrote:
The 6900K, for example, officially supports DDR4-2400 while there's word on the street that Ryzen officially supports DDR4-3600.

Ryzen is DDR4-2666. I'd wager that Intel's memory controller probably pulls more throughput than AMD so likely they'd end up similar in benchmarks. Important to note that those "official" specs only really matter if you're in the Intel H270/B250 or AMD H370/B360 platforms since the Intel Z270 (and likely the AMD X370) mobos support RAM speeds far in excess of the official CPU spec. Most/all Intel Z270 mobos support anywhere from DDR4-3600 to DDR4-4133.
Main: i5-3570K, ASRock Z77 Pro4-M, MSI RX480 8G, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, EVGA 550-G2, Silverstone PS07B
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Kougar
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Fri Feb 24, 2017 10:20 am

Also keep in mind Intel designed it's quad-channel Xeons to have up to 14 cores on them, the consumer parts are just an afterthought. May not matter for six cores, but double that to 12 then having 4 channels probably comes in handy.
 
Vhalidictes
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Fri Feb 24, 2017 12:12 pm

For 8 cores or less, memory channels don't matter except for some scientific benchmarks that are memory-sensitive.

If we were still on DDR3 I'd recommend it for a higher-end system just to be safe, but with the continual increases in effective bandwidth this is becoming less and less of an issue.

( Now if only newer memory types had decent latency /gripe )
 
whm1974
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Fri Feb 24, 2017 12:53 pm

Vhalidictes wrote:
For 8 cores or less, memory channels don't matter except for some scientific benchmarks that are memory-sensitive.

If we were still on DDR3 I'd recommend it for a higher-end system just to be safe, but with the continual increases in effective bandwidth this is becoming less and less of an issue.

( Now if only newer memory types had decent latency /gripe )

I was wondering about memory bandwidth issue myself. I was also thinking for six to eight cores dual channel memory will work fine for most use cases.
 
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Re: Ryzen System Build Planning - System Memory 4-ch vs 2-ch

Fri Feb 24, 2017 1:02 pm

whm1974 wrote:
I was wondering about memory bandwidth issue myself. I was also thinking for six to eight cores dual channel memory will work fine for most use cases.


For my current socket 2011v1 system I've noticed a minor performance increase when running multiple instances of VirtualBox when I populated the other channels, but that's got to be a tiny corner case.

Even among people who know what that is, most don't use it regularly.

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