AMD’s Ryzen 7000 Zen 4 architecture explained: Here’s its plan to lead in single-thread performance

The next generation of AMD microprocessors for desktop computers is on the way. Two days ago Lisa Su, the general director of this company, took advantage of the start of Computex, which is being held this week in Taipei (Taiwan), to publicize some of the features that the Ryzen 7000 processors will have. And they look really good .

The Ryzen 5000 have left the flag very high, and, in addition, Intel has stepped on the accelerator in terms of global performance with its 12th generation Core processors with Alder Lake microarchitecture. Given the circumstances, it is clear that AMD cannot afford to make a false move. And if we stick to what we know about the Zen 4 microarchitecture looks like it won’t.

There are still many details about the Ryzen 7000 processors that we do not know, but AMD has revealed the information we need to form a fairly accurate idea about what they are offering us. And one of the most important improvements that, in theory, will come from the hand of these chips is an increase in performance in single-thread applications of more than 15%. This is how AMD plans to battle its competitors.

Ryzen 7000 processors vs. their predecessors

The ‘chiplets’ continue, but the 5nm photolithography arrives

AMD has made many good decisions during the development of the generations of Ryzen processors that it has placed on the market, and one of them has been to bet on the implementation of chiplets. This strategy requires splitting the logic that until recently processor manufacturers packed into a single chip into several different integrated circuits that are packaged in a single package. This simply means that when we remove the heatsink that covers the processor’s printed circuit board, several chips will be exposed, and not just one.

There are two kinds of chiplets: IOD (Input Output Die) and CCDs (Core Complex Die). The CCDs incorporate the cores and the cache memory subsystem, among other essential elements of the CPU, while the IOD contains the main memory access logic and handles the interfacing of the CCDs and communication with the CPU. chipset from the motherboard. In Ryzen 5000 microprocessors the CCDs are made using 7nm FinFET photolithography, but the IOD is produced by 12nm integration technology.

The next Ryzen 7000 will maintain this same organization scheme, but the photolithography that TSMC will use in its manufacture will be more advanced. In fact, the CCD will be produced using the same technology of integration of 5nm that this semiconductor manufacturer is already using to produce chips for Apple or Huawei, among other companies, and the IOD will use 6nm integration technology. The introduction of more advanced photolithography will help increase the performance per watt of the Ryzen 7000, but this is only one of the ingredients in the recipe.

The other fundamental ingredient of the future Ryzen 7000 is its microarchitecture. We still don’t know many important details about Zen 4, such as what improvements it will introduce in the branch prediction algorithms of the code, what innovations it will implement in the execution pipeline or how it will solve the management of multiple cache sublevels, among many other design decisions in which the Ryzen 7000 will possibly stand out from its predecessors, the Ryzen 5000.

However, what AMD has already revealed is that the integrated graphics that some processors of the Ryzen 7000 family will offer us will be designed taking as a starting point the RDNA 2 microarchitecture. This is the same technological base on which the GPUs of the Radeon RX 6000 family are built, so at first glance it seems like the way to go. However, this is not all.

We also know that AMD engineers have redesigned the CPU’s building blocks and algorithms that are directly involved in processing threads (threads) in which it should prevail the minimum possible consumption, and not so much to achieve maximum performance. Increasing performance is critical, but so is keeping the CPU’s thermal power consumption and dissipation level under control. And it is clear that with these decisions the AMD technicians seem to be determined not to leave any loose ends.

In Zen 4 the level 2 cache is twice as large as in Zen 3

The impact that the cache memory subsystem has on the overall performance of a microprocessor is profound. It imports the scheduling policy for the information to be stored in the different cache sublevels, but its size also matters. And in this field the Ryzen 7000 are going to take a firm step forward by double the capacity of the level 2 cache. In this way each core will have at its disposal in Zen 4 an L2 cache of 1 MB, while in Zen 3 each of them had ‘only’ 512 KB.

What AMD has not yet confirmed is how it will implement the level 3 cache of the Ryzen 7000, but we can be reasonably sure that some of these processors, probably the most ambitious, will bet on 3D V-Cache technology. A little over a month ago we thoroughly reviewed the Ryzen 7 5800X3D chip, which is the first of this brand for desktop computers to implement this innovation, and it left us with a great taste in our mouths in our test bench.

3D V-Cache technology has already been used by AMD in some of its professional solutions, such as EPYC processors for data centers. Broadly speaking, it makes it possible to stack chiplets, so that instead of being placed next to each other, they are placed one on top of the other. In this way it is possible to notably increase the capacity of the level 3 cache memory, and, in addition, the latency of this subsystem is reduced. At the moment it is only speculation, but it is likely that some Ryzen 9 and 7 processors from the 7000 family will support this technology.

Going beyond 5 GHz is crucial to increase single-thread performance

In the first paragraphs of this article I have mentioned that AMD has made public its intention that the Ryzen 7000 processors increase in more than 15% its performance in single-wire applications. If in a real use scenario they show this increase in productivity, their performance in multithreaded applications will also be noticeably increased.

In any case, in addition to the contributions that the Zen 4 microarchitecture will make, which will undoubtedly be important, it is also crucial to increase the maximum clock frequency that the cores that bind the CCDs are capable of reaching. AMD ensures that its next processors will be able to work at a maximum clock frequency greater than 5GHz.

In fact, in one of the videos that he has published, a prototype of a possible Ryzen 9 of the 7000 series appears. working at 5.5GHz. The Ryzen 9 5950X that we can currently buy is capable of working at a maximum clock frequency of 4.9 GHz, and those additional 600 MHz added to the improvements introduced by the Zen 4 microarchitecture invite us to foresee that, indeed, the increase in 15% in single-thread applications that AMD promises us is feasible.

With the AM5 socket, DDR5 memories and the PCIe 5.0 interface will arrive

The AM4 socket that has accompanied the latest generations of AMD microprocessors has its days numbered. And it is that the Ryzen 7000 will arrive from the hand of a new platform known as AM5, and its protagonist will be a new LGA-type socket that will have a 1718-contact interface. This mechanical interface will be compatible with processors that will have a maximum TDP of 170 wattsand, obviously, it will force us to change the motherboard of our PC if we want to get hold of one of the new Ryzen 7000.

However, the adoption of this new platform will come hand in hand with the introduction of DDR5 memories and the PCI Express 5.0 connection interface. In addition, along with its new processors, AMD will launch three different chipsets: the X670 Extreme, which will be the solution offered by premium motherboards with slots for two graphics cards; the X670, for which high-end motherboards will bet; and, finally, the B650, which will be the one that the mid-range motherboards will incorporate. The arrival of Ryzen 7000 processors later this year It promises us a most exciting final stretch of 2022.