AMD architecture explained
Typically going for more cores per chip than Intel, the current range of AMD chips still performs strongly – even if new architecture is coming later this year
While Intel has opted for a complicated architecture, mixing performance cores with efficiency ones, AMD has stuck with a more traditional architecture for its CPUs. The current generation of chips on review uses the Zen 3 architecture, with the Ryzen 5 5800X3D the last chip of that generation before AMD introduces new processors that will use the brand-new AM5 socket.
With this range of processors, AMD largely decided to go for many cores per chip, boosting performance in multithreaded applications in particular. Thanks to its efficient
7nm manufacturing process (Intel is still on 10nm), a large number of cores can be used without the chips getting too hot.
As a result, while some of these processors are more than a year old, they still hold up well to Intel’s latest and greatest, particularly when you measure performance against price. Here’s everything you need to know about AMD’s chips.
Core design
Zen 3 is the natural evolution of the older Zen 2 architecture. While both use the same 7nm process, Zen 3 has been built to be more efficient with a fine-tuned architecture. AMD says that at the same clock speed, Zen 3 chips perform 19% better than their predecessors by implementing more instructions per clock; strangely, the exact performance increase that Intel quotes for its new chips.
Zen architecture is built around core complexes, which hold a certain amount of cores. With Zen 2, the core complex was limited to four cores, each sharing 16MB of L3 cache. For higher-core processors, multiple core complexes had to be installed. Intercommunication between core complexes introduces latency, so multithreaded applications could suffer as a result.
With Zen 3, the core complex has been upgraded to support up to eight cores, supporting 32MB of L3 cache per complex, as well as 512KB of L2 cache per core. This makes the architecture simpler in many regards and cuts the communication latency between complexes.
With Ryzen 7 and below, there’s only one core complex per chip; the Ryzen 9 chips add two complexes for either 12 or 16 cores in total.
While Intel uses Hyper-Threading to double the number of threads that can be run per core, AMD has a similar Simultaneous MultiThreading (SMT). This lets each core run two concurrent processes, making the number of threads double that of the core count. So, a 16-core Ryzen 9 processor runs 32 threads. On a pure thread count, AMD still trumps Intel.
As with Intel’s architecture, AMD’s processors run at two different clock speeds. The base clock speed is the processor’s speed when idle and the minimum that it will run at. Then there’s the Boost clock speed, which is where the processor will boost if it’s cool enough. That’s a good reason to buy a more expensive cooler: so you can get the maximum clock speed for as long as possible.
When comparing processors, it makes sense to compare the boost clock speed, as this is where the chips will spend most of their time when they’re pushed.
As AMD’s architecture is more standard, there’s no fancy software support needed to get the most out of it, so these chips will run as fast on Windows 10 as on Windows 11.
Thanks to that 7nm manufacturing process, the Zen chips have a lower TDP than Intel ones, with processors either a modest 65W or more powerful 105W. Actual temperatures during testing do vary, though, as you can see from our results in the table on p76.
Zen 3 chips perform 19% better than their predecessors by implementing more instructions per clock
Chipsets
All Ryzen processors use the AM4 socket, which has been around for many years. AMD is generally good at providing updates that let newer processors run on older chipsets, while Intel typically requires new motherboards for new processors, even if the socket hasn’t changed.
The current chipsets that support the range of processors include the X570, B550, A520, although older 3XX chipsets such as the A320 are also supported. That’s everything from high-end gaming boards to
entry-level budget motherboards for more basic computers. And, as the boards have been available for a good while, the prices are generally cheaper than the comparable Intel boards. Plus, if you have an older AMD system, you can upgrade to a new processor without having to change anything else.
If you’re going to use an older chipset that requires a BIOS update, you’ll need an older processor compatible with the board while updating it. Some resellers will offer a BIOS update service before shipping a board, but it’s good to check that your chosen processor will work with the board that you’ve chosen.
DDR4 memory
With older motherboards and processors, the crop of AMD processors that we have on review only support DDR4 memory, not the newer DDR5. That’s not so much of a problem today, as DDR5 memory is relatively expensive (not to mention in short supply), and the first batch is little faster than the highest-rated DDR4 RAM. Over the next year or two, however, we’d expect memory to transition to DDR5, but it’s not going to make a huge difference to most people; in fact, even with Intel, buying DDR4 today makes a lot of sense from a bang-per-buck standpoint.
PCI-E 4 support
AMD chips currently only support PCI-E 4 (bar the Ryzen 5 5500, which is PCI-E 3), rather than the newer PCI-E 5 standard. Is that a problem? Not really. Intel processors support PCI-E 4 to the M.2 storage slots, using PCI-E 5 for graphics cards and storage. However, there’s currently no PCI-E 5 storage available, and the first kit looks set to be for servers.
Practically, it’s going to take a while before we need the benefits of PCI-E 5, and you can buy some very fast M.2 drives already. Most AMD boards will take two M.2 drives.
3D V-Cache
At this point, we have to point out the AMD Ryzen 7 5800X3D, which is a new processor in the lineup. This is the first consumer AMD CPU to use 3D V-Cache. It works by adding an additional 64MB of L3 cache per compute complex. In the case of the 5800X3D, that means 96MB of L3 cache, compared to just 32MB on the standard 5800X.
The main benefit of 3D V-Cache is improved performance in games, although other workloads don’t see the same kind of performance increase. Think of this as a mid-priced, gamingorientated processor that’s built to deliver gaming performance on a par with the most expensive chips, and you get the idea of it.
Variations
AMD processors are split into three types: Ryzen 9, Ryzen 7 and Ryzen 5. All of them have the same basic core architecture.
Ryzen 9 is AMD’s top-of-the-range home CPU. These all have two core complexes, with a choice of either a 16-core or 12-core processor. Drop down to the Ryzen 7 lineup and you get a single core complex with eight cores. When you get down to the Ryzen 5 level, you get a single core complex with six cores in it.
Prices adjust in line with the number of cores and CPU speeds in the lineup. Our reviews will help you make the right decisions.
Within the ranges, you’ll see some models have an “X” in the name, such as the Ryzen 9 5950X. This means that the processor is unlocked so that you can manually overclock it to get more performance. This is the AMD equivalent of Intel’s “K” processors.
OEM models
AMD has a lot of processors that are sold to OEMs only. For example, the Ryzen 9 5900 is a locked version of the Ryzen 9 5900X but is only available to manufacturers. It’s a shame in some cases, as the OEM models look like they brilliantly balance price and performance. We’ve only reviewed models that you can buy.
Graphics
None of the processors that we’ve tested has onboard graphics on them. Instead, AMD has a line of so-called APUs that include graphics. These have similar model names to the regular processors but have a “G” at the end; CPUs with similar model numbers should have similar with or without the G.
The APUs don’t include products in the Ryzen 9 or Ryzen 7 lineups, featuring Ryzen 5 processors only. It’s generally assumed that if you want the best performance, you’ll buy a graphics card, while those looking for entry-level computers will buy a Ryzen 5 with integrated graphics.