AMD Zen 3: Exploring the Next Gen Architecture

AMD’s Zen Architecture was unarguably the most significant technological leaps for x86 CPUs in this decade. AMD reached even greater heights with Zen 2, and their current roadmap looks more promising than ever.

Today, we will take a deep dive into AMD’s upcoming Zen 3 Architecture and unravel their plans for 2020.

I’ve divided this article into two major sections. The first section will contain everything that AMD has officially confirmed. And in the second one, we will discuss the rumors and try to speculate the performance gains and specs of the SKUs.

I’ll continue to update this post as we move closer towards the official launch.

    Officially Confirmed Information

The following details have been officially confirmed through AMD at various presentations at different events.

  • Ryzen 4000 Series will continue to support AM4 Socket
  • Ryzen 4000 is codenamed ‘Vermeer’
  • TSMC’s 7nm+ EUV Process will be used
  • The whole CCD will now share L3 Cache
  • AMD could further increase the L3 Cache
  • It will use DDR4 Memory
  • 3rd Gen EPYC will support the same SP3 Socket
  • Zen 3 will support PCIe 4.0 just like Zen 2
  • 3rd Generation EPYC is codenamed Milan
  • EPYC Milan will launch in Q3 2020

Disclaimer: Even though the above details have been confirmed officially by AMD, some stuff can still change as time goes on. It has been written in some of the slides that ‘Roadmaps are subject to change.’

AM4 Support & Codenames

AMD’s CEO, Dr. Lisa Su, has mentioned it quite a few times about their commitment to the AM4 Platform. Here’s an official slide that confirms that AMD’s 2020 Desktop CPU will be on AM4.

AMD Roadmap till 2020

Image Source: Informatica Cero

Although the slide is from 2018, it is unlikely that AMD would change their existing plans to keep Ryzen 4000 on AM4. They also don’t have any reason for switching to another socket in the first place as they are sticking with the same DDR4 Memory for Zen 3. Furthermore, if they switch the socket now, it will only last one generation as DDR5 is expected in 2021 with Zen 4.

However, this slide didn’t end up being true for 3rd Gen Threadripper as it requires the new sTRX4 Socket.

Whether the 1st Gen Chipsets (B350 & X370) will support 4th Gen Ryzen will remain uncertain. It is mainly due to the limitations of the BIOS chip sizes. But AMD and the Motherboard manufacturers will likely find a workaround by creating a Zen 3 exclusive BIOS that will drop the support for previous-gen chips. We will only be able to find more information on it during the product launch in 2020.

The above slide also confirms that the Ryzen 4000 is codenamed Vermeer.

TSMC’s 7nm+ Node

Zen 3 will be fabricated using TSMC’s refined 7nm+ Process. It has already been confirmed by AMD multiple times.

AMD Zen Roadmap

TSMC’s 7nm+ Node (N7+) is their 2nd Generation of 7nm Process with some critical layers processed using EUV (Extreme Ultraviolet Lithography). The new N7+ process will allow 20% higher transistor density. It will also provide a 10% higher performance or 15% better power efficiency. AMD will likely opt for the former.

You can learn more about different Fabrication Nodes from this article.

On AMD Financial Analyst Day, Zen 3 is revealed to be on 7nm but it is more likely that AMD doesn’t want to reveal which variant of 7nm will it be.

AMD CPU Roadmap

While there is a slim possibility of AMD sticking with N7 or go with N7P, but that is extremely unlikely.

As the older slides showed 7nm+ (N7+), it should be true as you can’t change the fabrication process after designing a microarchitecture. The only scenario where N7 or N7P is possible is when all the earlier slides stating 7nm+ were false.

The yields of TSMC’s N7+ are also now on par with N7.

TSMC N7P Defect Density

Image Credits: TSMC

Unifying & Increasing the L3 Cache

Zen 3 will now unify the L3 Cache.

Zen 3 vs Zen 2 Cache CCX CCD

If two cores on separate Core Complex (CCX) have to communicate with each other, they had to do it through the Infinity Fabric. This results in a latency penalty, which was a disadvantage over Intel’s ring bus interconnect.

The L3 Cache from one CCX also needs to be shared via the Infinity Fabric, resulting in higher latency. While a small part of the problem can be addressed through the OS (By first scheduling all the process threads to one CCX before moving to the second one), it still isn’t good enough for those applications that can utilize a higher number of cores.

With Zen 3, the L3 Cache will be shared by the whole Core Complex Die (CCD).

Hence, instead of having two CCX on a chiplet, there will only be a single CCX. It will significantly reduce the latency that was involved with sharing the data between Cores that were on a separate CCX.

The performance benefits of unifying the cache could vary for different applications. But when it comes to gaming, this could result in a decent boost in performance. Maybe this could end up being AMD’s secret ingredient to surpass Intel’s upcoming Comet Lake CPUs in gaming.

If you check the above image, you’ll find a + sign next to 32 MB L3 Cache in Milan. This is clearly indicating that AMD will likely increase the L3 Cache just like they did with Zen 2. 

The increase in L3 Cache was already a significant contributor to Zen 2’s Higher IPC. So, AMD wouldn’t miss the chance to take more advantage of the same.

TSMC’s 7nm+ Node will allow a 20% Higher density, and I believe that a good part of it could go to the L3 Cache. But so far, we don’t know how much of an increase we can expect. I do not expect doubling the L3 Cache again as there will not be enough space even after an increase in the density.

DDR4, SP3, PCIe 4, and Q3 Launch

This slide gives a detailed look at AMD’s next-gen Architecture. Firstly, AMD will continue with DDR4 Memory for another generation, which was just as expected.

The 3rd Generation EPYC CPUs that will succeed Rome are codenamed Milan.

Zen 3 Milan Details

The next-generation server CPUs will stay on the current SP3 Socket and support PCIe 4, as Zen 2 does. PCIe 5 will likely arrive with Zen 4/Zen 5 in 2021/2022.

64/2X shows that AMD is going to continue with 2-Way SMT for Zen 3. The rumors for 4-Way or 3-Way SMT could either be for Zen 4 or for something else that AMD is planning. It is also possible that SMT4 will only be exclusive to just a few Milan SKUs.

If you’ll see the timeline for the Production of Milan in the above image, it is sometime in the middle of Q3 2020. I’m expecting both Ryzen 4000 & EPYC Milan to drop sometime in Q3 or early Q4.

On Finacial Analyst Day, AMD revealed that 3rd Gen EPYC will start shipping in later 2020.

3rd Gen EPYC Launch

Based on these new details, I expect 4th Gen Ryzen to ship in late Q3 and EPYC Milan in Q4.

    Rumors & Speculation

Everything that will be discussed in this section should be taken with a grain of salt. It can either end up being 100% false or completely true. Here’s what I expect from Zen 3:

  • Ryzen 4000 will be the last generation on AM4
  • About 8-16% IPC Increase
  • About 200 MHz Higher Boost Clocks
  • Lower Memory Latencies
  • Zen 3 will have even better Power Efficiency
  • Increase in Core counts unlikely but still a possibility (The top-end Ryzen 9 would still have 16 cores).
  • Slightly higher overclocking headroom
  • Gaming Performance could match or surpass Comet Lake
  • Productivity Performance to be higher than Comet Lake at the same Core/Thread Count

The Last Generation on AM4?

While AMD has informed many times about their commitment to AM4 Socket, they have also talked about its support until 2020. As Zen 4 in 2021 will likely support DDR5 Memory, it will make sense for AMD to move to a new socket (AM4+ or AM5).

AM4 Socket Compatibility

Hence, it is very likely that 2020 could be the last year for AM4.

IPC & Clock Speed Gains

With Zen 2, AMD managed to surpass Intel in IPC. They’re now very close to Intel in Single-Threaded Performance even with a vast difference in the clock speeds. AMD increased the IPC through various architectural enhancements.

Some of the most significant contributors in performance enhancements were doubling of the L3 Cache, Better Branch Prediction, Better Instruction & Cache Prefetching, Better Memory Controller, and increasing the floating-point performance.

Zen 2 Performance Contributors

Image Source: TechPowerUp

According to the above slide, AMD achieved a 21% boost in Single-Threaded Performance at Cinebench with Zen 2. For that 21% increase, the increase in IPC improvements contributed about 61.5% while the 7nm Node and Higher frequencies contributed 38.5%.

That 38.5% Improvement was due to moving from GlobalFoundries 12nm Node to TSMC’s 7nm Node. We can’t directly compare these two fabrication processes as they’re from two different companies, and it’s more of a marketing number. But it was a jump of more than one Full Node, and it was huge. With TSMC’s 7nm+ Process, AMD will gain 10% Higher Performance over the 7nm Process in Zen 2.

At SC19 conference, AMD hinted that with Zen 3 we can expect gains as high as one would expect from an entirely new architecture. Thus, I’ve changed my earlier prediction for an IPC increase from 6-12% to 8-16%.

With 4th Gen Ryzen, I’m expecting 100-300 MHz Higher Boost Clocks. When it comes to the improvements in IPC, I’m expecting around 8-16% improvements due to enhancements in the CPU architecture.

When we combine the improvements due to IPC and Boost Clocks, I’m expecting a 14-20% Performance uplift over Zen 2. We can also hope for about 200 MHz higher all-core Boost Frequency than the previous generation.

There should also be slightly more overclocking headroom, but nothing too exciting.

But the question remains, will Zen 3 touch 5 GHz?

It could reach that mark, but I would say so for only the highest-binned Ryzen 9 chip. Ryzen 9 4950X (if there will be one) should have a Single-Core boost speed of 4.9 or 5.0 GHz.

Memory Latencies

Even though AMD improved the support for High-Speed Memory with Zen 2, the memory latencies are still too high when compared to Intel’s Coffee Lake Refresh.

3rd Gen Ryzen Memory Latency Sweet Spot

We already know that optimizing Memory sub-timings using the Ryzen DRAM Calculator brings the memory latencies from 70-75 ns to around 62-65 ns. We also have a guide for the same.  The reduction in latencies also results in a massive FPS boost in games. It clearly indicates that improving the latencies would be one of AMD’s top-priorities while designing Zen 3 if they have plans to surpass Intel in gaming.

I’m expecting some improvements in the Memory Controller that will help with the latencies. 

Remember, Zen 2’s I/O Die is still on 12nm (14nm for EPYC Rome). Whether AMD will shrink it to 7nm (or 10nm?) will depend on whether the performance gains due to a 7nm I/O Die are worth the extra cost associated with TSMC’s 7nm Silicon over GloFo’s 12nm. We might get more information on that at CES 2020.

Before I speculate the specs, here’s an incredible die shot of Zen 2 by Fritzchens Fritz.

Zen 2 Chiplet Die Shot

Image Source: Fritzchens Fritz

How much do you think AMD will be able to increase the L3 Cache with the help of a 20% Density increase on 7nm+?

Expected Specs of Ryzen 9 4950X, 4900X, Ryzen 7 4700X, and Ryzen 5 4600X

When it comes to the Core Count, 4th Gen Ryzen will either have similar core counts, or we will see 2 extra Cores on Ryzen 5 & Ryzen 7 and all the Ryzen 9 SKUs might have 16 Cores.

SKU Ryzen 5 4600 Ryzen 5 4600X Ryzen 7 4700X Ryzen 9 4900X Ryzen 9 4950X
Number of Cores / Threads 6/12 or 8/16 (less likely) 6/12 or 8/16 (less likely) 8/16 or 12/24 (less likely) 12/24 or 16/32 (less likely) 16/32
Boost Frequency 4.5 GHz 4.6 GHz 4.7 GHz 4.8 GHz 4.9 GHz
MSRP $199 $249 $329 $499 $749

In the above lineup, I’m assuming that Ryzen 7 4700X is the highest binned Ryzen 7 chip, and there’s no 4800X.

Whether AMD will be able to increase the Core count for their entire lineup will depend on multiple factors. First and foremost, it will depend on the yields. And secondly, it will depend on the competition Intel brings with its 10th Generation Comet Lake CPUs.

If Intel launches the Core-i5 10600K at $249 with Hyper-Threading enabled, it could give a decent competition to Ryzen 5 4600 & 4600X. AMD will lose its massive advantage in Multi-Threaded workloads, with both chips being at 6 Cores/12 Threads.

In case AMD manages to outperform Intel in gaming even by just 1 or 2%, they can continue to stick with the same core count. But if i5-10600 is slightly better in Gaming when compared to Ryzen 5 4600 or the 4600X, AMD will be interested in going with 8 Cores at that current price to become the clear choice among consumers.

Don’t forget that it is likely the last generation on AM4, so it can also influence new PC builders not to move on AM4. AMD’s going to lose the ‘future compatibility’ advantage with Ryzen 4000.

Now, let’s see how yields can affect the Core counts.

If we look at the data from (A German Retailer) from their September 2019 Sales, for every 1 Ryzen 9 3900X they sold, they also sold 3.05 Ryzen 7 (3700X & 3800X) and 4.17 Ryzen 5 (3600 & 3600X).

Mindfactory CPU Sales Ryzen Zen 2

Image Source: Reddit User u/ingebor

Yes, the data is from only one retailer that sells in one country and Ryzen 9 sales are lower due to unavailability and 3950X is yet to launch, but we needed something to begin our analysis with. While the 3900X uses two Chiplets with two 6-cores enabled in each, Ryzen 5 has a single 6-core chiplet, and Ryzen 7 comes with a single 8-core chiplet.

If we multiply the number of chiplets with the sales data of the current Ryzen CPUs, 6-core chiplets are being sold 2.02 times more than 8-core ones chiplets. Yes, the higher quality 8-core chiplets are currently being saved for 3950X, Threadripper, and EPYC Rome. But the same situation will also arrive with Zen 3, so we can ignore that factor for now.

If Ryzen 5 has 8 Cores, Ryzen 7 has 12, and Ryzen 9 has 16, then AMD will have to sell 2.02 times more 8-core chiplets than the 6-core ones. That’s the exact reverse in the case of Zen 2.

However, AMD could utilize those defective 6-core chiplets and launch a Ryzen 3 lineup.

Now, if we count the total chiplets required to make a 3rd Gen Ryzen 5, Ryzen 7, and Ryzen 9 3900X CPU, the answer us 1+1+2 = 4. If we do the same for 4th Gen CPUs with higher cores, the answer will be 1+2+2 = 5. The cost of that extra chiplet in Ryzen 7 would probably not be feasible even if the yields are good.

It is still achievable if TSMC ramps up the production, and the yields improve due to a mature node and EUV Lithography.

The upcoming Playstation 5 and Xbox Scarlett shouldn’t affect the Zen 3’s 7nm+ production as they will use a custom 7nm Based Zen 2 CPU + Navi GPU instead.

So, in my opinion, the increase in Core Counts with Ryzen 4000 is less likely, but there’s still a good chance. If that’s what the competition demands and IPC gains aren’t enough for AMD to take a big lead over Intel, AMD will likely go for it.

Matisse vs. Comet Lake vs. Vermeer

As we already know, Intel’s Architecture is currently tied with the process. As they’re continuing with 14nm Node, Comet Lake will be the 4th Refresh of Skylake Architecture after its first introduction in 2015. Whatever progress Intel has made so far on 10nm with Sunny Cove & Ice Lake won’t be applicable to their Desktop parts.

Intel will improve the performance using the same trick they have been using for the last 3 Generations, i.e., refining the process (14nm+++) to achieve higher clock speeds. The improvements in the IPC would be minimal. In various leaks, we have seen that Intel’s upcoming flagship CPU will have 10 Cores and 20 Threads. It might also have a boost clock speed of around 5.2 GHz. It is expected to be priced similar to the Core i9-9900K.

Intel is also expected to enable Hyper-Threading on its entire 10th Gen Lineup to compete with AMD in Multi-Threaded performance.

Here’s what I expect in the Desktop CPU market for 2020.

Expected Scenario After the Launch of Comet Lake (Intel’s 10th Gen Desktop Chips)

  • The 3rd Gen Ryzen 9 CPUs will continue to dominate Intel’s 10th Core-i9 CPUs in Productivity Performance due to higher core counts
  • Intel’s 10th Gen CPUs will have slightly higher clock speeds but at the cost of higher power consumption & heat output
  • 10th Gen Core i5 & i7 Chips will match 3rd Gen Ryzen 5 & 7 in Productivity due to Hyper-Threading Support
  • Comet Lake CPUs will have a marginally better Gaming Performance that will help Intel dominate AMD in all price segments

Expected Scenario After the Launch of Vermeer (AMD’s 4th Gen Ryzen Chips)

  • 4th Gen Ryzen Processors will dominate Intel’s entire 10th Gen Lineup in Productivity due to better IPC & Clock Speeds
  • Depending on the extent of IPC Gains & Latency Improvements, 4th Gen Ryzen’s Gaming Performance could range anywhere from being on par with Comet Lake at worst-case or 5-6% better than Intel at best-case
  • Vermeer will be far more power-efficient than Comet Lake

    Zen 4: Even bigger performance leap?

Just like the previous section, it is mostly based on speculation as well. Rumors point out that Zen 4 could be fabricated using TSMC’s 5nm HPC Node and will support DDR5 RAM.

Just like TSMC’s 7nm Node, their 5nm Process has two variants in which one is optimized for Mobile while the other is optimized for HPC. It is 1.8 times denser than the 7nm Process.

On AMD Financial Analyst, AMD confirmed that Zen 4 will be using TSMC’s 5nm HPC Node.

AMD Genoa Roadmap

Just like AMD’s was obsessed with the number ‘7’ for Zen 2 (7nm and launch on 7/7), I’m expecting a similar trend with Zen 4 but with the number ‘5’. But this time around, they can take this obsession to a whole new level with 5nm Process, DDR5, PCIe 5, SP5 Server Socket, AM5 Mainstream Socket, and 5th Gen Ryzen.

Here’s what I’m expecting from Zen 4, which is currently in design (as of late 2019).

  • Performance gains by moving from Zen 3 to Zen 4 could be even higher than they were from moving to Zen 2 (from Zen+).
  • More than 12% IPC improvement
  • TSMC’s 5nm EUV Node (Confirmed)
  • DDR5 Memory Support
  • 4th Gen EPYC CPUs codenamed Genoa (Confirmed)
  • X3D Packaging (Confirmed)
  • 3rd Gen Infinity Architecture (Confirmed)
  • SP5 Socket for EPYC
  • AM5 Socket for Ryzen
  • 3-Way or 4-Way SMT is possible (Or could be exclusive to EPYC and/or Threadripper)
  • PCIe Gen 5 support is possible
  • With a 1.8 times increase in Transistor density, a single Zen 4 chiplet could consist of 12 or 16 Cores
  • Zen 4 could have HBM dies on CPU as L4 Cache
  • Top-end Ryzen chip could have 24 or 32 Cores
  • Launch in late 2021

Before moving to PCIe 5, the motherboard manufacturers will likely want to figure out how to dissipate heat better. I’ll instead prefer a Motherboard with PCI Gen 4 that can dissipate heat passively than the one that supports Gen 5. The current PCI-E 4.0 NVMe drives like Corsair MP600 & Aorus NVMe Gen4 have massive heatsinks, and yet they end up getting extremely hot on extended usage. It doesn’t make much sense having those 5 GB/s Sequential Speeds when it can’t be maintained for long durations.

With the help of 5nm die shrink, Zen 4 based Ryzen, Threadripper, and EPYC CPUs will have higher cores. The top-end Ryzen 9 chip could potentially have 24 or 32 Cores.

On Financial Analyst day, AMD also shared a few details on X3D Packaging. We will likely see AMD’s 3D Packaging for the first time in 2021 with Zen 4.

X3D Packaging

    Final Words

Whether you’re cheering for Intel or AMD, one thing you’ll agree on is that x86 CPUs were crawling towards a slow death. But in 2017, AMD stepped in and made things interesting again. By increasing the Core Count in 2017, AMD widened the performance gap between ARM and x86 based CPUs in Highly-Threaded Applications.

Now the upcoming Zen 2 based Renoir (7nm) & Sunny Cove based Ice Lake (10nm) will further increase the performance gap against ARM-based chips like Snapdragon 8cx. These new architectures will also be extremely power efficient when compared to the previous-gen 14nm/12nm CPUs.

Whether ARM or RISC-V will take over in the next decade is surely an exciting topic, but we should save it for another day.

Should you Build a PC now or wait for 4th Gen Ryzen?

This has always been a topic of debate whether you should buy the current best product or wait for the next generation. The answer from my side will always be different based on the performance gains that are expected and how far we are from the product’s launch. With 4th Gen Ryzen, I’m expecting good performance gains just as high as what AMD managed to do with Zen 2.

If you’re reading this post in the last quarter of 2019 or the first quarter of 2020, go with 3rd Gen Ryzen. But if you’re reading it sometime after May/June 2020, I would recommend waiting a few months before you build or upgrade your PC.

Also, don’t forget that you might get some great discounts on 3rd Gen SKUs a few months prior to the launch.

1 thought on “AMD Zen 3: Exploring the Next Gen Architecture”

  1. Good review, however I wished you hadn’t included this bit here:
    `Many people also believe that AMD could go with TSMC’s 6nm Node but considering AMD’s current roadmap of ‘Process Shrink then Optimization’ or what Intel calls as ‘Tick-Tock,’ 5nm looks like a better choice as it is a proper die shrink from 7nm Node.`

    This is incorrect. Tick (shrink node jump) Tock( introduce new architecture) has been Intel strategy until Kabylake release, with seemingly 10nm trouble ahead, they went ahead and defined Process (Broadwell, node jump) Architecture (Skylake, Architecture) Optimization (Kabylake). So far, Looks like Intel will continue optimizing(Coffee lake and possible Coffeelake Revision?) until 10nm in desktop finally becomes a thing.

    As for Zen(tick+tock), in AMD history, it jumped both Node and improved architecture drastically, on their own slide, they claimed 52% IPC increased compared to Excavator core.
    Zen+(refresh), just makes a node jump with marginally performance and fixed memory latency, tweaked memory controller and introduced Precision boost 2. However, it makes no major performance difference from Zen, I’d consider Zen+ a refresh.

    Zen 2(tick) is a big node jump as it finally moves away from GF and adopts TSMC superior node and introduced TAGE branch predictor and brought themselves a massive performance increase.

    Zen 3 Should be a Tock. Several AMD executive has stated that they’re bringing a new architecture with a 7nm EUV on the market for Ryzen 4th gen.

    Personally, i’d stick Process Optimization Architecture reserved for Intel, as AMD continue to implement Tick Tock strategy with TSMC continuing to offer a shrink Node


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