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AMD Confirms DDR5-6000 as "Sweetspot" Memory OC Frequency for Ryzen 7000

btarunr

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AMD in its Discord AMA confirmed DDR5-6000 to be the "sweetspot" memory overclock for its upcoming Ryzen 7000 "Zen 4" processors. A sweetspot frequency in AMD jargon is an inflection of performance, stability, cost, and ease. For the very first Ryzen, this was DDR4-3200. For Ryzen 2000, it was DDR4-3400. For the Ryzen 3000 "Zen 2," it climbed to DDR4-3800, the Ryzen 5000 "Zen 3" it was DDR4-4000.

At the architectural-level, it is usually the highest frequency where FClk, UClk, and MClk maintain a 1:1:1 ratio, before having to engage dividers that impact performance, making it a point of diminishing returns for investing in faster memory modules. AMD's Robert Hallock, leading the Discord AMA, recommended that FClk be left untouched at "Auto" for the best results, and overclockers look for an Auto:1:1 ratio for the FClk, UClk, and MClk. As with both AMD and Intel now, the highest frequencies are possible only with one single-rank DIMM per memory channel (1DPC), and memory overclocking yield lower results with dual-rank DIMMs, or two DIMMs per memory channel. Among the AMD EXPO-certified DIMMs announced over the past few days, some do engage memory clocks beyond DDR5-6000. It would be interesting to see how they affect the "golden ratio" for Zen 4.



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Wondering after the last "leak" how exactly AMD achieved a 3000MHz Fabric and 1:1 UMC monumentally superior to Intel's in the same generation............this is literally just same old unsynced Fabric. Robert trumpeting "1:1" ratio (wow that was misleading) for UMC:mem means nothing. On Ryzen you break sync with Fabric, not the UMC (has 1:2 U:M ever been a thing??). I guess the new feature this time around is further decoupling UMC from mem clock (Gear 2-style), maybe to facilitate higher DDR5 records?

1733MHz default Fabric sounds like a big step up over 1066MHz but that probably just from DDR5 JEDEC speeds being higher. Robert using 2000MHz FCLK as an example suggests not much has changed and it's still the same slow-ass Fabric links in there, minus generational improvements for slightly higher clock. And optimizations to lessen the unsync penalty since it's the norm now.

Although, Fabric isn't strictly bound to 1:1/2/4 ratios like Intel IMC is, so maybe that's what Robert meant by Auto FCLK - you just let Fabric run as high as it can. iirc on AM4 there was some performance improvement to keeping Fabric fast even if desynced; it just didn't get much attention because no one ran desynced daily.
 
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"2 DIMMS are always better than four"

wrong

for Ryzen, 4 ranks has always been best, the difference in performance between 2 vs 4 ranks can be almost 10% in games, plenty of benchmarks / reddit / famous German overclocker videos show that

now, finding dual rank DDR4 isn't easy (not sure about DDR5), both 8 and 16GB sticks are coming as single rank nowadays, so having 2x8 or 2x16GB will give you dual rank and you're gonna have LESS performance than a 4 stick 4 rank system. A 4 rank 2 sticks would be better yes, but hard to find.

so for the past 1-2 years on Ryzen 3000/5000, the best doable performant build on Ryzen has been 4x8GB single rank, running fclk 1:1, between 3600 and 4000 MHz with the tightest timings possible
 
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Same as "usual" Uncore and IF from legacy AM4 it seems, I suspect it needs particular timing like first gen Ryzen for overclocking. Good thing AMD pushed EXPO preventing drama.

edit :

"2 DIMMS are always better than four"

wrong

Um no, 2 DIMM are better than 4, dual ranks are better than single, so in perfect condition 2 DIMM dual ranks DDR4 3600Mhz PC4-28800 CL14 give highest performance.
 
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"2 DIMMS are always better than four"

wrong

for Ryzen, 4 ranks has always been best, the difference in performance between 2 vs 4 ranks can be almost 10% in games, plenty of benchmarks / reddit / famous German overclocker videos show that

now, finding dual rank DDR4 isn't easy (not sure about DDR5), both 8 and 16GB sticks are coming as single rank nowadays, so having 2x8 or 2x16GB will give you dual rank and you're gonna have LESS performance than a 4 stick 4 rank system. A 4 rank 2 sticks would be better yes, but hard to find.

so for the past 1-2 years on Ryzen 3000/5000, the best doable performant build on Ryzen has been 4x8GB single rank, running fclk 1:1, between 3600 and 4000 MHz with the tightest timings possible

You're totally correct, although I think dual rank 16gb chips are reasonably common (unlike 8gb) but yeah, getting much above 1800mhz is very rare, 1900mhz is like a golden sample, and maybe only Dr. Lisa Su can hit 2000mhz.
 
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"For Ryzen 2000, it was DDR4-3400. For the Ryzen 3000 "Zen 2," it climbed to DDR4-3800, the Ryzen 5000 "Zen 3" it was DDR4-4000."

That is highly misleading." Sweetspot" can't be something a lot of processors can't achieve, and these numbers aren't guaranteed or even commonly achevable. Ryzen 3000 with Infinity Fabric at 1900 MHz and Ryzen 5000 with Infinity Fabric at 2000 MHz were rare.

There was a company, now gone, that pre-binned the processor for you, that claimed that only 14% of 3900X could achieve IF 1900, and that was Zen 2 with highest success rate. I guess they could be exaggerating to justify the high price, but there were a lot of reports of people that couldn't achieve these "sweetspots" with top of the line processors and very expensive RAM.
 
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More like 3600 and 3800 for zen2/zen3
 
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"2 DIMMS are always better than four"

wrong

for Ryzen, 4 ranks has always been best, the difference in performance between 2 vs 4 ranks can be almost 10% in games, plenty of benchmarks / reddit / famous German overclocker videos show that

now, finding dual rank DDR4 isn't easy (not sure about DDR5), both 8 and 16GB sticks are coming as single rank nowadays, so having 2x8 or 2x16GB will give you dual rank and you're gonna have LESS performance than a 4 stick 4 rank system. A 4 rank 2 sticks would be better yes, but hard to find.

so for the past 1-2 years on Ryzen 3000/5000, the best doable performant build on Ryzen has been 4x8GB single rank, running fclk 1:1, between 3600 and 4000 MHz with the tightest timings possible
It depends heavily on high much you can tune your memory, then your MB & CPU i.e. silicon lottery. I have 64GB (4x16) & 128GB (4x32) setups on Ryzen & I don't see the 10% extra you're talking about, application & workload will also make a big difference. Though you are right about the point that generally speaking 4 DIMM's will probably max out performance for Zen uarch, especially wrt what I've seen on Intel in the past. Maybe that's just an IF quirk or something?
 
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"For Ryzen 2000, it was DDR4-3400. For the Ryzen 3000 "Zen 2," it climbed to DDR4-3800, the Ryzen 5000 "Zen 3" it was DDR4-4000."

That is highly misleading." Sweetspot" can't be something a lot of processors can't achieve, and these numbers aren't guaranteed or even commonly achevable. Ryzen 3000 with Infinity Fabric at 1900 MHz and Ryzen 5000 with Infinity Fabric at 2000 MHz were rare.

There was a company, now gone, that pre-binned the processor for you, that claimed that only 14% of 3900X could achieve IF 1900, and that was Zen 2 with highest success rate. I guess they could be exaggerating to justify the high price, but there were a lot of reports of people that couldn't achieve these "sweetspots" with top of the line processors and very expensive RAM.

No idea why that is in the article. It is False.

Here is the Zen 2 slide



3733 is sweet spot not 3800 as stated in the article. Some could do 3800 but it was a lot harder.

For Zen 3 they didn't have such a chart but they did have this slide



Where they state 4000 for Zen 3 is about the same difficulty as 3800 for Zen 2. That is not at all like saying 4000 is the sweet spot. For Zen 3 3800 was considered the sweet spot.

Historically AMD have used the sweet spot to describe the highest speed that can be achieved by the majority of samples so if AMD are describing 6000 as the sweet spot then that can probably be done by the vast majority of samples rather than it being like 4000 on Zen 3 where only a few samples can do it.
 
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I don't think AMD ever talked about "majority of samples". I think these were presented as "best case scenario", with perhaps rare better processors - you even have "good luck!" on Zen 3 slide for the sweet spot. :)

"Performance sweet spot" just meant that higher DDR speeds surely lost the 1:1 IF sync for most of users, and lost quite a bit of performance.
 
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I don't think AMD ever talked about "majority of samples". I think these were presented as "best case scenario", with perhaps rare better processors - you even have "good luck!" on Zen 3 slide for the sweet spot. :)

"Performance sweet spot" just meant that higher DDR speeds surely lost the 1:1 IF sync for most of users, and lost quite a bit of performance.

If it was best case scenario they would have picked 3800 for zen2 because it was doable on some samples.

Their sweet spot has always been an inflection point of cost, performance, % of samples that can hit that speed.

The likening of 4000 on Zen3 to 3800 on Zen2 is to illustrate that some samples can do it but you need a good sample. Otoh 3733 is far easier to achieve on zen2 and 3800 on zen3 hence why AMD picked 3733 as the sweet spot.

Have you not noticed over the last 5 years when it comes to Ryzen AMD have tried very hard to be realistic with the claims they make. They actively try not to mislead people. This sweet spot stuff is just another example, DDR5 6000 will probably be pretty easy to achieve unless you get really unlucky. Faster will get harder quicker so I expect 6400 to be like 3800/4000 was for Zen2/3, doable but you need a bit of luck.

EDIT. In any event AMD self described the Zen 2 sweet spot as 3733 in that slide so the article stating "For the Ryzen 3000 "Zen 2," it climbed to DDR4-3800" is simply not true and should really be corrected. Given that the claim for Zen 3 is also untrue because AMD likened 4000 to 3800 which would also mean that 4000 is not the Zen 3 sweet spot as claimed in the article.
 
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Their sweet spot has always been an inflection point of cost, performance, % of samples that can hit that speed.

...

Have you not noticed over the last 5 years when it comes to Ryzen AMD have tried very hard to be realistic with the claims they make. They actively try not to mislead people. This sweet spot stuff is just another example, DDR5 6000 will probably be pretty easy to achieve unless you get really unlucky. Faster will get harder quicker so I expect 6400 to be like 3800/4000 was for Zen2/3, doable but you need a bit of luck..

But in reality we don't have any real data on how achievable those "sweet spots" really are. Sure, you can gather tons of anecdotal data, but this is mainly from enthusiasts (which are the only ones that even bother with memory, IF optimization). How many of them have exchanged their CPU back because it didn't achieve the targeted IF?

Remember when Zen 3000 CPUs didn't achieve their boost frequencies? No reviewer even mentioned this, and it took a wide poll by an enthusiast (Der8auer) which showed that majority of users didn't achieve processor's bacic spec:

"The worst is the Ryzen 9 3900X, which only reaches the Boost frequency in 5.6% of cases."

Has anyone done anything similar for IF frequency? No, and the reason is AMD never promised anything in this regard. Some even defended AMD with boost frequency scandal, the spec was written as "up to" in some material. So not guaranteed, apparently.
 
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Has anyone done anything similar for IF frequency? No, and the reason is AMD never promised anything in this regard. Some even defended AMD with boost frequency scandal, the spec was written as "up to" in some material. So not guaranteed, apparently.
AMD manages the frequency by AGESA too.
A few months after launch they locked PBO boost on 5600x to max 4850MHz from more than 5100Mhz on a single core. Silently with no explanation why.

 
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But in reality we don't have any real data on how achievable those "sweet spots" really are. Sure, you can gather tons of anecdotal data, but this is mainly from enthusiasts (which are the only ones that even bother with memory, IF optimization). How many of them have exchanged their CPU back because it didn't achieve the targeted IF?

Remember when Zen 3000 CPUs didn't achieve their boost frequencies? No reviewer even mentioned this, and it took a wide poll by an enthusiast (Der8auer) which showed that majority of users didn't achieve processor's bacic spec:

"The worst is the Ryzen 9 3900X, which only reaches the Boost frequency in 5.6% of cases."

Has anyone done anything similar for IF frequency? No, and the reason is AMD never promised anything in this regard. Some even defended AMD with boost frequency scandal, the spec was written as "up to" in some material. So not guaranteed, apparently.
If you can gather enough samples you can see a trend so go check techspot (HUB), TPU, GN, LTT perhaps, ComputerBase, HardwareLuxx etc to see if they did memory scaling tests and to see if they disclosed how many samples hit certain speeds like techspot did. If you can get 20 or so samples then you can start to see a trend.

Besides my point is the article says Zen 2 was 3800 sweet spot when this is explicitly untrue, AMD said 3733 was the sweet spot for Zen 2. AMD didn't really mention a sweet spot for Zen 3 but they did state that 4000 on Zen 3 was akin to 3800 on Zen 2 which would mean above the sweet spot since 3800 is above the sweet spot so the article is incorrect to refer to those memory speeds as the sweet spots for Zen 2 and Zen 3.
 
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If you can gather enough samples you can see a trend so go check techspot (HUB), TPU, GN, LTT perhaps, ComputerBase, HardwareLuxx etc to see if they did memory scaling tests and to see if they disclosed how many samples hit certain speeds like techspot did. If you can get 20 or so samples then you can start to see a trend.

Reviewers usually don't report the outliers and obviously substandard products, they get them replaced silently - it's not really relevant to statistics if you recieve one item and that one item turns out to be a "defect".

But what can be a clear defect for a reviewer can be a product hard to replace for a normal buyer, especially if we're talking about the stat that has no clear guarantee.

That's why you get launches of products that have very high rate of failure or are even DOA in high percentage - but no reviewer mentiones that. Until it is publically known, and then they candidly admit they had to RMA the product several times before they could do a review.

So I wouldn't be surprised if absolutely every reviewer's Ryzen achieved the "sweet spot" IF frequency.

I mean, no reviewer even mentioned trouble to achieve Ryzen 3000 boost frequency, and then the poll showed that it was more of a fluke if you actually got one that did that.
 
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Doesn't this just basically indicated quad pumped FCLK MT/s is about what you can expect from between 1733 FCLK to 2000FCLK or more precisely 6932MT/s to 8000MT/s. The latter being around what we've heard as the reported theoretical limits of DDR5 standard. Also closer to 1:1 ratio's have generally always been ideal for synchronization across buses, but it can often drift some and end up better or worser for various interconnected buses to a minor degree less favorable or more favorable.
 
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If 1733 FLCK i standard and 2000 is almost the top OC then there would basically be no need for speeds above 4000MHz unless you rund memory in 1:2 configuration?
 
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So I wouldn't be surprised if absolutely every reviewer's Ryzen achieved the "sweet spot" IF frequency.

If you had checked you would know this is incorrect.

TPU could not get their 3700X sample above 1800 fclk when the 'sweet spot' was 1867.

None of TechSpots Zen 3's managed 2000 fclk although all could manage 1900 fclk.

2 of TechSpots Zen 2's managed 1900 fclk but 2 others topped out at 1800 fclk.

This is just from a cursory glance.

Again though, my point is that this:

For the very first Ryzen, this was DDR4-3200. For Ryzen 2000, it was DDR4-3400. For the Ryzen 3000 "Zen 2," it climbed to DDR4-3800, the Ryzen 5000 "Zen 3" it was DDR4-4000.

is false for Zen 2 and Zen 3. Zen 2 sweet spot was 3733 according to the AMD slide. And AMD never really said anything about Zen 3 sweet spot other than that DDR4-4000 would be about as likely as Zen 2 hitting DDR4 3800 1:1 so above the sweet spot.
 
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You're totally correct, although I think dual rank 16gb chips are reasonably common (unlike 8gb) but yeah, getting much above 1800mhz is very rare, 1900mhz is like a golden sample, and maybe only Dr. Lisa Su can hit 2000mhz.
yeah so I built my 5800X last black Friday and I couldn't find on Amazon US / AU any decent 32GB quad rank kit with 2 sticks - by decent I mean 3600C16 and costing <200USD. Tried BHPhoto as well, don't have access to Newegg or Microcenter.

So in the end I bought a 4x8GB Crucial 3600C16 and overclocked it to 3800C16 while lowering some timings, and it has been rock solid on all memory benchmarks I throw at it.

Just checked now and a decent DDR5 6000 kit is going for 290 USD on Amazon, ~110USD more than what I paid for the Crucial...
 
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Ok for us plebs that don't have master in memory, what will be the best config for Zen 4. Say I want 64Gb, do I buy 2 single/dual rank 32GB sticks or 4 single/dual rank 16GB sticks?
 
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