On Mon, Aug 19, 2019 at 12:10 PM D. Hugh Redelmeier via talk <talk@gtalug.org> wrote:

One of the features of the latest round of Ryzen chips is support for PCI 4.0.

In practice, PCI 4.0 isn't very important yet: current video cards don't saturate PCI 3.x and neither do NVMe SSDs. But NVMe SSDs that exploit PCI 4.0 are starting to be announced.

There is a chicken and egg problem: until there are a lot of systems that can support PCI 4.0, few devices will be built to that spec.

I was very disappointed to learn that AMD, in a firmware update, has disabled PCI 4.0 support for all consumer motherboards except those based on the very expensive x570 chipset.

Their excuse was that some motherboards weren't built to reliably support PCI 4.0. Surely they could have left that up to the discretion of the MB manufacturer (through whom these firmware updates flow).

The motherboard must be engineered for PCI 4.0. But it could be built with the cheaper X470, X370, B350, and A320 chips. No longer.

<https://old.reddit.com/r/Amd/comments/buydi6/amds_robert_hallock_no_pcie_40_support_on_300_and/epn2c83/>

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Hugh, I would agree. Most modern bus updates are to the protocol not wiring so why not allow it. There concern is the extra power requirements but that should be up to the motherboard vendors to decide that. The problem for them is I believe that some of the lower end boards for older chipsets are able to meet requirements but not higher end ones making some customers angry or they assume. Again this seems to be more of a customer relationship issue rather than a hardware issue. PCI 4.0 is a big deal at least for storage through the drives run hot. https://www.pcgamer.com/dont-forget-the-heatink-for-your-crazy-fast-pcie-40-... Through PCI 4.0 is able to do 100gbps at x8 I believe so that's useful for data centers. Nick