Finding a full speed PCIE 5.0 to PCIE 4.0 bridge / adapter / switch / riser / etc?

Hardware Hub Motherboards
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Are there existing (maybe even supermicro server proprietary ones), PCIE 5 to PCIE 4 converter, which makes full use of the PCIE 5 bandwidth ?

Meaning adapting for example a single PCIE-5.0 x 16 slot, to full 4 * PCIE-4.0 x 8 slots

I vaguely recall a short aside demo card for a server, to be used with nvme/u.2 which would not be able to make use of the full PCIE 5 speed anyway. As part of a video for a server. But can’t seem to find it.

( I have no idea if im hallucinating, or it was servethehome / level1tech / etc … )

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I don’t think you could achieve this with just a retimer. Those are mostly used to push these fragile signals through cables not really made for it (miniSAS PCIe5 risers with retimers for example exist). To actually get more usable lanes out than you put it, I imagine you need a bridge, even if you do go down in per lane speed to maintain the same total bandwidth.
I’d check with someone like Christian Peine Contact Us – C-Payne PCB Design if there is anything like that in the pipeline.

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Yea, good point that retimer makes zero sense (edited title)

Probably more likely a bridge or switch (likely one of those broadcom chips)

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Keep us updated. :slightly_smiling_face:

I’ve been scoring the web from time to time with no results. :pensive:

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The closest i have found - which is not what i initially remembered. Are PCIE 5.0 switches / risers.

Like: G293-S43 (rev. AAP1) | GPU Servers - GIGABYTE Global
( this server has 4 riser with PCI5 switches in built)

and : Expansion Backplane, 5 PCIe x16 5.0 slots (580) - One Stop Systems

I legitimately want to know if GIGABYTE have a parts supply program (like supermicro), and how much those risers will be when they are out lol

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This second one appears to be a non-starter: it uses 100 W.

But the first one, I imagine, could be made to work with downstream PCIe 4.0 devices with a bit of planning.

The these would appear to be great for PCIe CEM-to-MCIO/MiniSAS setups using C-Payne’s device adapters to “move” the slots to a more convenient part of the chassis.

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The riser card that G293 uses is based on the PEX89088 chip : https://docs.broadcom.com/doc/BC00-0445EN

So we are looking at 33 W or higher :thinking:

I think the general idea seems to be instead of gen5 → gen4
Is simply having enough gen5 switches, with enough bandwidth for the split gen4 lanes.

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Looking for a three-generation jump here: 5.0 → 2.0. :joy: Too many devices still lagging behind with PCIe 2.0 speeds on the market and they’re like 8~16 lanes wide. :unamused: But PEX89144 is the only one that multiplies 16 lanes to 128, and it sucks up 49 W. :sob:

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How many PCIe 2.0 cards do you want on a single server? :thinking:

With the avg prices of these things, you might as well hit one of those 10+ pcie slot servers

There is also the PEX89048 risers, which is 23.7W : G293-S42 (rev. AAP1) | GPU Servers - GIGABYTE Global

Which is 1 x PCIe5.0 → 2 x PCIe5.0 slot

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