In a surprising twist, AMD has today announced that it intends to enable Ryzen 4000 and Zen 3 support on its older B450 and X470 Motherboards. This is going to be a ‘promise now, figure out the details later’ arrangement, but this should enable most (if not all) users running 400 series AMD motherboards to upgrade to the Zen 3 processors set to be unveiled later this year.


When AMD launched the Ryzen 3 3300X and Ryzen 3 3100 processors, it also gave users details about the upcoming B550 chipset that these processors were targeted for. Part of that announcement included a chart, showing how due to BIOS limitations, certain chipsets would only support certain AM4 processors. X570, for example, would support previous Ryzen 2000, current Ryzen 3000, and future Ryzen 4000 processors – it did not support the original Ryzen 1000 processors.

On that chart, it was noted almost immediately that there was a glaring omission. AMD’s B450 and X470 motherboards were listed as supporting Ryzen 1000/2000/3000, but not the future Zen3-based Ryzen 4000 processors. This made a number of users immediately very concerned, especially if they had purchased a B450 or X470 motherboard with a Ryzen 3000 processor with the hopes to upgrade it in the future.

AMD came under a lot of fire. The company had originally promised that it would support the AM4 platform from 2016 through 2020 (or ‘through to’ 2020). A lot of users had assumed that this meant any AM4 platform based motherboard would be able to accept any processor made from 2016 to 2020, including the new Zen 3 processors set to be unveiled later this year. The fact that there was a discrepancy between what the users expected and what AMD had been saying essentially became a miscommunication or a misunderstanding, but one that had a negative effect on a number of users who were expecting to upgrade the system.

Ultimately the reason for the lockout was down to the BIOS size. Each generation of processors require a portion of the BIOS space for compatibility code – normally if you can support one processor from a generation, then you can support them all. We are also in the era of graphical interface BIOSes, and as a result some of the BIOS code was reserved for fancy menus and the ability to adjust fan curves or update the BIOS in a more intuitive way. All of this takes up space, and some vendors ditched the fancy graphics in order to support more processors.

Most AMD motherboards are outfitted with 128 megabit (16 megabyte) BIOS chips. The reason why this is the case is due to a limitation on some of AMD’s early AM4 processors – due to design, they can only ever address the first 16 megabytes of a BIOS chip. So even if a motherboard vendor had a larger BIOS chip, say MSI had a 32 megabyte chip, then it would actually operate like two partitioned BIOSes and it would get very complicated. There is no easy way to support every AM4 processor with a simple 16 megabyte BIOS.

By our estimate there are 84/86 current processors on the AM4 platform in total, counting Ryzen Pro parts as well. These are set across several families (A-Series, Zen, Zen APU, Zen+, Zen+ APU, Zen2, Zen2 APU, etc), each with their own AGESA platform to deal with, which all has to go into the BIOS. This is what makes it such a tight squeeze.

As a result AMD initially made the decision that the B450/X470 motherboards would support the Ryzen 1000, Ryzen 2000, and Ryzen 3000 processors, but would not be able to support any more due to this limit. AMD ultimately wanted the 500-series chipsets, the B550/X570, to be a launchpad for the future Ryzen processors.

AMD’s Announcement Today

AMD today is reversing its decision to limit the BIOSes on the 400-series chipsets. To cut a long story short, the TL;DR mantra from AMD is:

‘We’ve heard our audience, and we understand the concerns. We are going to work out a way to support Zen 3 on our 400-series chipsets between now and launch – we’re still working out the what and the how, but we will update you closer to Zen 3 launch’.

They are acknowledging that they perhaps misread the situation from its user base. Part of this issue stems from an old CPU line not having the growth room, and the believed that pushing support for Zen 3 to the 500-series wouldn’t be that big of an issue. Now that they see it is, they will try to make it work. They will attempt to address the technical challenges, and even though they do not have all the details at this time, it will be worked on.

There is still 6+ months (?) until we see Zen 3, so they do have a lot of time to try things and to test things.

In conversations with AMD, we also discovered more insight into what this entails.

As most motherboards have 16 MB, and the CPUs can only address the first 16 MB of a BIOS chip, then we might see an issue where 400-series motherboards may end up having two ‘forked’ BIOSes – one for ‘up to Ryzen 3000 inclusive’ and one for ‘Ryzen 3000 and beyond’. The former one will likely be a default BIOS, which will be picked up by auto-update software, however the latter will likely always be a Beta BIOS, and it will require user intervention.

AMD will enable the ODM partners with the feature – partners like ASUS, GIGABYTE, Dell, HP, MSI, Lenovo, etc. However, it will be up to the ODM partner to actually enable it as a feature for their motherboard or pre-built system. If they’re not willing to complicate matters with this BIOS fork, then unfortunately you are out of luck. It is believed however that if most of the vendors are onboard straightaway, then the rest will follow. AMD will be offering continual support to its ODM partners on this, especially those with auto-update software.

There might be a situation where moving up to the beta BIOS fork will make the system unable to downgrade. It might end up being a one-way solution. It might even be a hard changeover – with the mainline supporting 3000 and below, and the fork 4000 and up. In this event, I asked AMD if they would be expanding the Boot Kit program as they did with Ryzen 2000, and lending CPUs to users that needed them to update. AMD stated that this might be a possibility, but they haven’t worked on those details at this time.

AMD reiterated to AnandTech that after the launch of B550 into the market, they do recommend the B550 motherboards as the best option for Ryzen 4000 support in upgrades. However they will be working towards supporting Ryzen 4000 on 400-series chipsets for current users in that market, and to enable customers who want to go along that upgrade path. It is worth reiterating that even with Zen 3 CPU support, B450/X470 boards will likely be limited to PCIe 3.0 due to the design.

AMD also re-confirmed that we are set to see Zen 3 processors in 2020.

AMD AM4 Motherboard Support
AnandTech uArch A320 B350
X570 B550
Ryzen 4000 CPU Zen 3 X X Beta
Ryzen 4000 APU** Zen 2 X ? ? ? ?
Ryzen 3000 CPU Zen 2 X Beta
Ryzen 3000 APU Zen+ X
Ryzen 2000 CPU Zen+ X
Ryzen 2000 APU Zen X X
Ryzen 1000 CPU Zen X X
Athlon A-Series * X X X
Ryzen Pro CPUs follow their non-Pro equivalents
* Excavator or Carrizo
** Unknown - product not announced yet

AMD's full press release is given below.

As we head into our upcoming “Zen 3” architecture, there are considerable technical challenges that face a CPU socket as long-lived as AMD Socket AM4. For example, we recently announced that we would not support “Zen 3” on AMD 400 Series motherboards due to serious constraints in SPI ROM capacities in most of the AMD 400 Series motherboards. This is not the first time a technical hurdle has come up with Socket AM4 given the longevity of this socket, but it is the first time our enthusiasts have faced such a hurdle.

Over the past week, we closely reviewed your feedback on that news: we watched every video, read every comment and saw every Tweet. We hear that many of you hoped a longer upgrade path. We hear your hope that AMD B450 and X470 chipsets would carry you into the “Zen 3” era.

Our experience has been that large-scale BIOS upgrades can be difficult and confusing especially as processors come on and off the support lists. As the community of Socket AM4 customers has grown over the past three years, our intention was to take a path forward that provides the safest upgrade experience for the largest number of users. However, we hear you loud and clear when you tell us you would like to see B450 or X470 boards extended to the next generation “Zen 3” products.

As the team weighed your feedback against the technical challenges we face, we decided to change course. As a result, we will enable an upgrade path for B450 and X470 customers that adds support for next-gen AMD Ryzen™ Processors with the “Zen 3” architecture. This decision is very fresh, but here is a first look at how the upgrade path is expected to work for customers of these motherboards.

  1. We will develop and enable our motherboard partners with the code to support “Zen 3”-based processors in select beta BIOSes for AMD B450 and X470 motherboards.
  2. These optional BIOS updates will disable support for many existing AMD Ryzen™ Desktop Processor models to make the necessary ROM space available.
  3. The select beta BIOSes will enable a one-way upgrade path for AMD Ryzen Processors with “Zen 3,” coming later this year. Flashing back to an older BIOS version will not be supported.
  4. To reduce the potential for confusion, our intent is to offer BIOS download only to verified customers of 400 Series motherboards who have purchased a new desktop processor with “Zen 3” inside. This will help us ensure that customers have a bootable processor on-hand after the BIOS flash, minimizing the risk a user could get caught in a no-boot situation.
  5. Timing and availability of the BIOS updates will vary and may not immediately coincide with the availability of the first “Zen 3”-based processors.
  6. This is the final pathway AMD can enable for 400 Series motherboards to add new CPU support. CPU releases beyond “Zen 3” will require a newer motherboard.
  7. AMD continues to recommend that customers choose an AMD 500 Series motherboard for the best performance and features with our new CPUs.

There are still many details to iron out, but we’ve already started the necessary planning. As we get closer to the launch of this upgrade path, you should expect another blog just like this to provide the remaining details and a walkthrough of the specific process.

At CES 2017, AMD made a commitment: we would support AMD Socket AM4 until 2020. We’ve spent the next three years working very hard to fulfill that promise across four architectures, plus pioneering use of new technologies like chiplets and PCIe® Gen 4. Thanks to your feedback, we are now set to bring “Zen 3” to the AMD 400 Series chipsets. We’re grateful for your passion and support of AMD’s products and technologies.

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  • FreckledTrout - Tuesday, May 19, 2020 - link

    True socket support in the past meant CPU support but I simply don't see any reason to get outraged. It’s not like they are arbitrarily limiting support or Like Intel creating a new socket for no technical reason. They have real reasons of fitting all that AGESA code into the BIOS.
  • rarson - Tuesday, May 19, 2020 - link

    I agree with you completely on the outrage part. People are reacting a bit too extremely about this. But to me, this whole situation is a little disappointing for a few reasons. Primarily, I'm disappointed that AMD was caught so off guard by this problem, as BIOS limitations should have been pretty obvious before they started shoving everything onto AM4. Previous generation APUs had their own socket and I'm not sure why AMD felt the need to consolidate everything to AM4, especially the pre-Zen stuff like Bristol Ridge. They already had Zen, Zen+, Zen 2, and Zen 3 on the public roadmaps LONG before Ryzen was launched and should have known well before this that the CPU support list was going to become massive with all these different chips to support. Basically, it's a little embarrassing for a company who has manufactured CPUs for this long to run into this problem, let alone be blind-sided by it. I'll chalk it up to ambition, but they should have seen this coming.

    Also, CPU support based on the socket always made planning builds with future upgrades in mind a lot easier with AMD. Given that they have usually been the budget option, this is plus for their target audience, it makes going with AMD an even easier decision. If AMD wants to shift CPU support to the chipset, that's fine. I may not like it, but if that's what they determine they should do, then I accept that. However, it's not right to suddenly introduce this change when you're 75% of the way through your socket road map and many of your loyal customers bought in at the beginning under the assumption that the company would continue maintaining support the same way they had for decades.

    And honestly if they do shift to a chipset-centric support model (which, let's face it, they have because X370 support is done), that will make me think twice the next time I want to build an AMD computer. I'm not saying that I'm boycotting them or anything, just that I'll be a little more weary about CPU support.
  • JoeWright - Tuesday, May 19, 2020 - link

    Why'd you wait 4 years to complain about this?
    Couldn't you have made similar complaints right at the start claiming that amd failed to keep their promises because cpus like 1800x and cheap a320 mobos existed at the same time?
  • rarson - Tuesday, May 19, 2020 - link

    Part of the problem is that in the past, AMD has typically changed the socket when changing CPU support, and even then, as was the case with the "plus" sockets, still retained some compatibility between new and old boards and CPUs. Usually, AMD would announce the socket and state how long they intend to support the socket, and that was it. Intel on the other hand was always tied to specific chipsets, and the socket had no real bearing on what processors would be supported by a given board. This has always somewhat frustrated me about Intel, because you can never assume that a given chipset will support future processors. Case in point, I feel like anyone that invested in Z270 got really ripped off. That aside, I will give Intel a small bit of credit for avoiding this kind of mess completely by setting customer expectations.

    I built my first PC in 1997, and have always switched between AMD and Intel, based on my budget, the parts currently available, and the best bang for the buck with upgrade path in mind. Granted, parts are a lot cheaper than they used to be (graphics cards aside), but generally I start with a good motherboard and a cheap CPU so that I can upgrade down the road. It's ALWAYS been easier to plan very far ahead with AMD, because you knew that when they said they would support a socket for a number of years, the newer CPUs would work with all boards that used the same socket. In fact, when they first announced AM4, I assumed that meant that every AM4 board would support all CPUs up to and including Zen 3 (based on the timelines it seemed pretty clear that the third Zen iteration would arrive within that support window). It's a little frustrating to have AMD suddenly change CPU support without changing the socket after decades of doing the opposite. I would have rather seen them change the socket for Zen 3 than continue with the same socket while breaking support. But it's pretty clear they realized far too late that this BIOS thing would be a problem.

    I don't necessarily fault them for being overly ambitious, however it kind of makes you wonder why they bothered with stuff like Bristol Ridge on AM4 or why a company that has been making CPUs and chipsets for decades wasn't more aware of the BIOS problems arising from supporting too many CPUs on a single socket. If it comes down to removing BIOS graphics altogether and going back to a normal, plain menu interface then I'm all for it, as I really loathe useless BIOS graphics.
  • mkaibear - Tuesday, May 19, 2020 - link

    Actually, and I can't believe I have to keep pointing this out, it's closer to Intel: "We tried to make multiple generations work on the same socket before and we got absolutely *slated* by the enthusiasts and press when changing power budgets meant not every chip worked - so now we don't make promises about how long sockets will last"
  • rarson - Tuesday, May 19, 2020 - link

    Intel has never made promises about how long sockets will last, CPU support has always been tied to the chipset and not the socket.

    What Intel got blasted for is creating warmed over refreshes (Kaby Lake) and useless chipsets (Z270) fully aware of the impending release of higher core chips with Coffee Lake.
  • DigitalFreak - Tuesday, May 19, 2020 - link

    How many people really upgrade their CPU and keep the same motherboard? Seems like a solution looking for a problem.
  • ArcadeEngineer - Tuesday, May 19, 2020 - link

    Surely everyone if they could? What's the reason for a random consumer to throw away a perfectly good B450 board and buy B550?
  • PhysicsNurd - Tuesday, May 19, 2020 - link

    PCIe 4 NVME SSD support?
  • Ratman6161 - Tuesday, May 19, 2020 - link

    I recently upgraded from a 1700 + X470 to a 3700X + X570. But I almost decided to just put the 3700X in the X470 board. I don't currently have anything that takes advantage of PCIe 4 so there is really no performance advantage to be had from the motherboard upgrade. I mainly did it for future upgrades and because I could use the old motherboard and CPU in another system.

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