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Question AMD Rembrandt/Zen 3+ APU Speculation and Discussion

izaic3

Junior Member
Nov 19, 2019
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Alright, so we've had some leaks so far. I don't know if any of it's been confirmed yet, as it's pretty early, but here is what I've surmised so far (massive grain of salt of course):

If if turns out to have RDNA 2 and 12 CU, I could see iGPU performance potentially almost doubling over Cezanne.

If I've made any mistakes or gotten anything wrong, please let me know. I'd also love to hear more knowledgeable people weigh in on their expectations.
 
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Mopetar

Diamond Member
Jan 31, 2011
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What I'd be most interested in is whether the move to RDNA2 graphics technology also coincides with the inclusion of something like a shared L3/infinity cache between the CPU and GPU cores. APUs being particularly bandwidth constrained would see a big improvement on the graphical workload side and we've already seen many applications where Zen 3 has done well because of the larger cache available.
 

izaic3

Junior Member
Nov 19, 2019
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What I'd be most interested in is whether the move to RDNA2 graphics technology also coincides with the inclusion of something like a shared L3/infinity cache between the CPU and GPU cores. APUs being particularly bandwidth constrained would see a big improvement on the graphical workload side and we've already seen many applications where Zen 3 has done well because of the larger cache available.
Now that would be interesting. Do you know how RDNA CUs compare in size to Vega? Because if they're smaller, then that would leave more room for a larger cache.
 
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Mopetar

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I'm not sure off hand. Also what's being called Vega inside of AMD's APUs has probably changed a fair bit from we got from the initial launches all those years ago.

Even if a larger shared cache takes up additional room, it's hardly wasted space if both the CPU and GPU benefit.
 

izaic3

Junior Member
Nov 19, 2019
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I'm not sure off hand. Also what's being called Vega inside of AMD's APUs has probably changed a fair bit from we got from the initial launches all those years ago.

Even if a larger shared cache takes up additional room, it's hardly wasted space if both the CPU and GPU benefit.
I agree, it would definitely be beneficial. My concern is whether or not AMD will have the wafer capacity to make enough APUs that would have this extra cache. Granted I'm sure the silicon design was probably finalized before the current supply issues. I'm not suggesting they have multiple APU designs, both with or without the infinity cache, but I'm wondering if they figured that DDR5 would help the bandwidth issue enough to design the chip to not have infinity cache.
 
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uzzi38

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Oct 16, 2019
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Alright, so we've had some leaks so far. I don't know if any of it's been confirmed yet, as it's pretty early, but here is what I've surmised so far (massive grain of salt of course):

If if turns out to have RDNA 2 and 12 CU, I could see iGPU performance potentially almost doubling over Cezanne.

If I've made any mistakes or gotten anything wrong, please let me know. I'd also love to hear more knowledgeable people weigh in on their expectations.
Given AMD's yearly cadence of CES for launch of Ryzen mobile for the last couple of years it's probably safe to assume 2022 is when we should expect a launch. Otherwise, great list.
 

izaic3

Junior Member
Nov 19, 2019
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Given AMD's yearly cadence of CES for launch of Ryzen mobile for the last couple of years it's probably safe to assume 2022 is when we should expect a launch. Otherwise, great list.
Yeah, that makes a lot of sense. I had read somewhere that some think that Rembrandt will be kind of a stopgap solution (hence being the only series using the FP7 socket), and thus might be released earlier, but I find that to be unlikely as AMD mobile is competing quite well against Intel's mobile chips at the moment. Some of AMD's 15 watt chips are beating Intel's 35 watt chips (at least in multicore).

However, since Rembrandt is on TSMC's N6, I could see them trying to move to that sooner since it has ~18% higher density than n7+, and thus AMD might be able to crank out more chips (seeing as they're selling everything they make atm).

But, since Ryzen Mobile 5000 series processors are hardly available atm, it does seem weird to have them replaced in only a few months time.
 
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LightningZ71

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Mar 10, 2017
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The Vega CUs in Renoir and Cezanne are essentially unchanged from the ones in the Radeon VII card, which themselves we're almost completely identical to the original CUs in Vega 64/56. The only effective changes were in memory controller, buffering, and clock frequency as Vega 8 has been pushed to truly impressive numbers.

With the relatively modest density improvements in N6, I suspect that it will look a lot like Cezanne, but with the iGPU section expanded relative to the CPU cores. I don't think the L3 cache will be more than 16MB as it would make some significant changes in the die size to do so. 16MB is competitive in the segment, and DDR5 is a big boost in bandwidth.

I am of the opinion that performance will be in the ballpark of the RX560, likely the cut down CU version. That's nothing to sneeze at and likely will keep pace with the MX450 and perhaps surpass it in a few benchmarks.
 

moinmoin

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Jun 1, 2017
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Will be interesting to see whether the CPU part in Rembrandt sees significant improvements. To me it currently looks like AMD is content to alternate its APU cadence between significant CPU and iGPU upgrades.

But, since Ryzen Mobile 5000 series processors are hardly available atm, it does seem weird to have them replaced in only a few months time.
Nothing weird about that, AMD sells what it makes, and makes the quantity it planned to make. The assumed lack of availability of Renoir (which actually helped AMD reach its biggest laptop market share ever, so unprecedented demand, not lack of supply) didn't delay the launch of Cezanne/Lucienne either.
 
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izaic3

Junior Member
Nov 19, 2019
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Will be interesting to see whether the CPU part in Rembrandt sees significant improvements. To me it currently looks like AMD is content to alternate its APU cadence between significant CPU and iGPU upgrades.


Nothing weird about that, AMD sells what it makes, and makes the quantity it planned to make. The assumed lack of availability of Renoir (which actually helped AMD reach its biggest laptop market share ever, so unprecedented demand, not lack of supply) didn't delay the launch of Cezanne/Lucienne either.
That is true, though there was still a year between those releases yeah? Based off of benchmarks on various sites, there seems to be very few Ryzen 5000u series laptops in consumer hands atm (with many laptops not releasing until May or later). So if Rembrandt is released in 2021, it would be a maximum of 8 months from now. Just seems like a very quick turn around as product launches take a fair amount of time and effort on AMD's (and partner's) part. Granted they did it with the Ryzen 3000x vs 3000xt cpus, but I feel like that is a much smaller change than we're talking about here. However, if they're planning on launching in 2021 while continuing to produce Cezanne APUs, I could see that being helpful in meeting consumer/oem demand as they could use n7 and n6 simultaneously (which would make sense seeing as I don't think they can acquire more n7 currently).
 
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Mopetar

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Jan 31, 2011
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I agree, it would definitely be beneficial. My concern is whether or not AMD will have the wafer capacity to make enough APUs that would have this extra cache.
Cezanne already has 16 MB L3 cache, so this would just be doubling that and designing it in a way that it's accessible to the graphics units as well. The overall die size wouldn't increase too much.

As for wafer capacity, that's a separate issue and the answer is that they don't have enough now to make enough of anything. :p
 

eek2121

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Aug 2, 2005
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What I'd be most interested in is whether the move to RDNA2 graphics technology also coincides with the inclusion of something like a shared L3/infinity cache between the CPU and GPU cores. APUs being particularly bandwidth constrained would see a big improvement on the graphical workload side and we've already seen many applications where Zen 3 has done well because of the larger cache available.
Unsure about Rembrandt, but they are definitely working on infinity cache for Ryzen.
 
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uzzi38

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Oct 16, 2019
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Rembrandt tape-out was less than 6 months after Cezanne, I would be very surprised if it's a 2022 release.
It's also a brand new platform with plenty of validation etc to be done. Tonne of new platform features - USB4, PCIe4 etc etc. Plus, a yearly cadence is a big selling point amongst OEMs, they like that kind of consistency.

I dunno, my bets still on CES next year
 
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yuri69

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Jul 16, 2013
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Keep in mind there is also a room for a yet unknown Cezanne refresh (Renoir/Lucienne). 2022 for Rembrandt seems likely.
 

Kedas

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Dec 6, 2018
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So you re saying we see (LP)DDR5 sooner on the APU mobile market than on the Desktop market?
They do have a history that the APU comes much later than the CPU, not sooner.
 

uzzi38

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Oct 16, 2019
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So you re saying we see (LP)DDR5 sooner on the APU mobile market than on the Desktop market?
They do have a history that the APU comes much later than the CPU, not sooner.
Wasn't Bristol Ridge AMD's first DDR4 consumer product? It was certainly the first on AM4, so that argument doesn't hold up I don't think.
 
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Mopetar

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Wasn't Bristol Ridge AMD's first DDR4 consumer product? It was certainly the first on AM4, so that argument doesn't hold up I don't think.
It was, but I don't know if we can really draw any conclusions from that because it was released at a time where AMD had essentially quit making desktop chips because Bulldozer wasn't going anywhere and would only be replaced by Zen (which by then AMD would know was considerably more promising) in a year.

Meanwhile, APUs were still an area where AMD could compete and the Zen-based APUs wouldn't come out until the other segments had launched so there was plenty of room for a refresh for Carrizo.

I'm not saying that it couldn't happen, but just that the historical precedence for it is probably more of a circumstance of the position AMD was in at the time rather than anything else.
 

moinmoin

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So you re saying we see (LP)DDR5 sooner on the APU mobile market than on the Desktop market?
They do have a history that the APU comes much later than the CPU, not sooner.
Note that since Renoir the IMC is already more advanced than the IOD, allowing for truly async IF/memory clock ratios. I think AMD treats the APUs as test bed regarding I/O power optimizations. Introducing new IMCs there as well doesn't sound out of scope, especially since mobile platforms are more malleable than desktop/server platform where the platform specs are set in stone for years to come.
 

LightningZ71

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Mar 10, 2017
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Also, DDR5, as a solution, is naturally lower power than DDR4. It was one of the design goals. Since the APUs are mobile/integrated first, it makes sense to push them ahead with respect to IMC when there are tangible gains in both performance and power draw to be had.
 

Mopetar

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Jan 31, 2011
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I'm assuming that if it does have DDR5 memory that they'd release it on a new socket.

AM4 has had a pretty good life and it's hard to imagine anything else that hasn't already been announced supporting it.
 

Shivansps

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Sep 11, 2013
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Well, current rumors say that Warhol and Cezanne will be the last CPU/APU for AM4. And i think it is safe to say that this is correct.

For AM5/DDR5 Rembrandt and Raphael are expected, and some say that they are both APUs, what means this may be the end for CPU-only on mainstream desktop. As things are, it seems possible that Rembrandt may launch first on AM5 at the same time Warhol and Cezanne are still around on AM4, and that AM4 will only fully be replaced once Raphael launches.

On notebooks Vega will live on in Barcelo, likely a Cezanne refresh used to replace Lucienne on the low end.

Van Goth is a mistery, but it looks like as a embedded-only product.

I think we are missing the low end here, something along the lines of Dali.
 

Shivansps

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Sep 11, 2013
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Pollock are the ULV chips, basically a 5W 14nm Raven2 that they are trying to cram into ultra-portable, tablets, chromebooks, etc. Something that is doomed to fail and it is going to cause more damage than good, it seems that they will never learn.

Dali is the replacement of Raven2, it is based on 12nm, and has 4 cores, 4 threads and Vega 3. Used on the 3050GE (2C/4T) and 3150G(4C/4T). They are OEM only just like Renoir.

But since AM5/DDR5 is missing its "Dali", it is likely that the low end will live on AM4 with Dali and Cezanne for at least a year after AM5 launches, and in notebooks they hace Barcelo and Dali for this task.
This is why that, for a while, Van Goth looked like the Dali replacement, because it is a Zen2 Quad Core, but with 8 CU RDNA2? nah, impossible, thats too much, it also needs regular DDR support, not just LPDDR.Van Goth seems to be something else, and that leaves Dali without a replacement.

The problem with this is that this means Dali will stick around in the low end to, at least, 2023 if there isnt a planned replacement now. And Dali it is just a 3200G with Vega 3.
 

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