Following this week’s launch of AMD’s new Ryzen 3000 series of processors, reports have once again begun circulating that PCIe 4 will be available on some existing 300 & 400 series boards. This comes despite AMD’s official statement last month that they would not be allowing the feature on older boards, as PCIe 4’s tighter signal integrity standards would have led to, at best, a highly fragmented market where some boards work, some boards don’t, and some boards may be outright marginal. At the time the company stated that the feature would be stripped from the AGESA that goes into the final Ryzen 3000 launch BIOSes for older boards.

So, to get right to the heart of matters, I reached out to AMD PR this evening to find out what’s going on with PCIe 4 support. The short version then is that no, AMD’s plans have not changed: PCIe 4 support will be disabled in the shipping AGESA for these boards.

Our plan is unchanged. For the reliability and consistency reasons cited at Computex, we still intend to disable PCIe Gen 4 for pre-X570 motherboards. That AGESA is being released to motherboard manufacturers soon.

As things stand, any boards that currently support the feature would be using pre-release AGESAs, and as we’ve seen with our own BIOS issues, the Ryzen 3000 BIOS situation is still evolving fast. So with AMD intending to permanently disable the feature – and prevent any workarounds – AMD’s goals haven’t wavered. At best, the few boards that have beta BIOSes with the feature will lose them in the future, unless users opted to stick with an unsupported (and almost certainly buggy) BIOS.

Going forward, proper PCIe 4 support will continue to require an AMD 500-series board specifically designed to meet the signal integrity requirements for the higher speed standard. Right now, this includes boards based on AMD’s X570 chipset; and while the company hasn’t announced other 500-series chipsets, we’re expecting to see more in due time.

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  • Dijky - Tuesday, July 16, 2019 - link

    Zen2+ officially doesn't exist. The next step on the roadmap is Zen3.

    Granted, Zen+ didn't originally exist on the roadmap either.

    Anyway, I expect neither of these will feature PCI-E 5 or DDR5.
    Reply
  • cheshirster - Tuesday, July 16, 2019 - link

    "Having even a few models of older motherboards not work with PCIe 4.0"
    It's not only a few models.
    Every board with multiGPU support won't be able to run pcie4.0 on GPU's
    That's almost all x370, x470 boards and top of the line B350 boards.
    They could try to provide pcie4 only on NVME slots, but that mix might not be possible at all.
    Reply
  • azfacea - Saturday, July 13, 2019 - link

    I dont get whay you are nagging about? you want pcie 4 buy an x570 motherboard. the entry ones are pretty good. You do realize that if no1 buys pcie4 there is no way to pay for the cost of R&D right ??

    ppl don't buy new technology, than complain about lack of innovation ?
    its one thing to say i can't afford x570, i'll stick to b450. but than demand that some1 else pay for pcie4 to come to you is ridiculous.
    Intel won't even have pcie4 on comet lake and LGA1200, and you wont stop nagging about a 30 dollar premium
    Reply
  • azfacea - Saturday, July 13, 2019 - link

    messed up spelling and no edit feature
    sorry mens((
    Reply
  • eek2121 - Saturday, July 13, 2019 - link

    You don't understand how the BIOS/UEFI works for Intel/AMD. Intel and AMD have a core set of tweaks. OEMs provide a UI for those tweaks. If Intel/AMD remove the tweak, the OEM simply removes the UI for that tweak. In addition, if you dig into the BIOS using one of many tools, you can unlock hidden tweaks for nearly every board. For Zen 1 and Zen+, all those fancy "features" that manufacturers advertised were simply manipulating AMD CBS and PBS settings. From a BIOS/UEFI standpoint, there are actually no differences between manufacturers that are using the same AGESA version. Vendors simply customize their UEFI UIs to look 'flashier'. Reply
  • limitedaccess - Friday, July 12, 2019 - link

    Are we really buying AMDs reason? To me it seems more likely it's to push higher margin chipset sales (X570) but of course it's not PR friendly to state that. I'll also go so far as to say if it weren't AMD but competitors the reaction would also be more along those lines.

    I would bet most people would be mainly interested in PCIe 4.0 support on either the x16 and/or one m.2 slot. Judging by some third party validation data at the moment this seems very doable on existing boards.

    Instead you have to buy X570 at a higher price and deal with the higher power requirements and fan if you want any PCIe 4.0 at all. Good for extra chipset sales I suppose.

    As for board signal integrity it's not as if OEMs can't design new revisions or even new models but just using the older (and cheaper) chipsets.
    Reply
  • Qasar - Friday, July 12, 2019 - link

    wouldnt it be possible for AMD to not allow support for pcie 4 in the bios, no matter what though ?? if it cant be enabled in the bios, there is little oems can do... Reply
  • weilin - Saturday, July 13, 2019 - link

    That is correct, AGESA (AMD Generic Encapsulated System Architecture) is more or less the "foundational code on which BIOS files ... are built" to quote Anandtech. I don't believe this code is not modifiable by OEMs.

    It sounds like AMD is bundling support for the 3xxx series and the lock to PCIe 3.0 to the same AGESA release. Either the boards not going to POST or remain in fail safe mode, or it's going to recognize the 3xxx series CPU and be locked to PCIe 3.0
    Reply
  • 12345 - Friday, July 12, 2019 - link

    Having data loss on nvme drives or gpu driver bsods due to too little margin for signal integrity problems could be a pr nightmare. Reply
  • Sahrin - Saturday, July 13, 2019 - link

    I think you're dramatically overestimating the number of people who would choose X470 over X570 if they both supported PCIe4.0. Reply

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