Is it even possible on a technical level? Or would a switch of sorts be required for that.
You’d need a multiplexer
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It would also need mobo support tbch. Its not just a simple downgrade voila. Yes PCIE is backwards compatible but what your asking for is something to downgrade to 4 and send the traffic together through the 5.0 lane. Not sure if that would work with just a multiplexer?
Oldie but goodie
I feel like this should work with a multiplexer, but I’m not totally sure. There’s also not a lot of market options for these and it looks like very limited configuration options that are set per-device.
Definitely not just with motherboard bifurcation.
I don’t think pcie multiplexers will let you do that, they are blocking devices. Some, but not all, pcie switches will allow you to oversubscribe pcie peripherals to a host and auto negotiate different pcie phys on the trunks downstream ports.
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you would need a multiplexer that supports this.
most of them just use the same standard they are plugged into and given that pcie 5.0 is still very new its gonna be super expensive.
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Yes 3-4 cie do have card that do that. But as quite just nic card do run in gen5 and some gfx card in gen4 … the speed difference in a gen4 vs gen3 is about less than a 5%. But the price of the switch will be quite the opposite.
What you are describing I believe it possible but you would need two downstream switches, one to convert the 16 PCIe 5 lanes into two lots of 8 PCie Lanes which we will call A and B and then another switch to turn the 8 lanes from B into 16 lanes.
The catch - every time you go through a switch - you add a delay and its going to cost you $$$
Sigh, wish it was cheaper.
Would’ve loved to see modern mobos give us more x8/x16 pcie4 slots from the cpu instead of pcie5.
Some modern mobos do handle more bifurcation, I am not sure if it’s to the level that you want but you pay for it, my motherboard the Gigabyte X670E xtreme does but it cost $1300 NZD, not many people will pay for that “privilege” .
It’s not just a case of plexing tho, with converting lanes from PCIe5 to PCIe4 you are going to need a downstream switch - there is no avoiding it. You can change the lanes to what ever numbers you like but you can’t increase the number of lanes and downgrade to PCIe 4 at the same time. While PCIe5 is backward compatible what we are literally talking about doing here is taking half of the PCIe5 lines converting them to PCIe4 lines but doubling the number of lines to achieve PCIe 4 x 16 - a mux can only mux PCIe5 and can’t down convert to increase the number of lanes.
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