Can you split pcie lanes for one device (for example pcie 2.0 x1 to pcie 1.0 x2)

[Transpanda]

Thanks everyone for your replies. I do have a simple pcie x1 to x16 adapter which I’m currently using, a mining riser to be precise as my case is mATX. The reason I‘m interested in this is the that the thing im plugging in, a weird gpu originally for mining, is already limited to 1/16 of the normal pcie speed it should have. Plugging it into an x1 connection limits it to 1/64 which as you may guess does have a very mild impact on performance.

I did some more research on my own as well and it seems that a specialised chip for this doesn‘t exist and won‘t exist in the future either. It’s a niche and complicated part that barely anyone needs so even if it‘s possible it’s probably not commercially viable.
It would have to independently negotiate the pcie speed with the motherboard and gpu during post, combine or split all sent packages, speed or slow down the connections and somehow simultaneous manage the timing of two different frequencies. Additionally it would need a buffer for incoming and outgoing packets, introducing delay and therefore reducing the actual performance gain. This only gets more difficult the more lanes and pcie generation differences the pcie slot and device have.

Thanks again for your time and suggestions.

 

[Wirko]

It would have to independently negotiate the pcie speed with the motherboard and gpu during post, combine or split all sent packages, speed or slow down the connections and somehow simultaneous manage the timing of two different frequencies. Additionally it would need a buffer for incoming and outgoing packets, introducing delay and therefore reducing the actual performance gain. This only gets more difficult the more lanes and pcie generation differences the pcie slot and device have.

PCIe switch chips do all of that. All or most of those we've mentioned in this thread do that, and AMD/Asmedia Promontory chipsets belong here too.

Actually, I'm not sure if there's a standard terminology all manufacturers use (switch vs. bridge vs. multiplexer). Probably not. But there exist at least two categories of chips, and since Asmedia makes both, I'm taking their names as an example:
- ASM1480 is a "multiplexer / demultiplexer Switch", probably not even aware of PCIe protocols, and not able to do what you asked for
- ASM2806 is a "packet switch" that can be found in the "PCIe Bridge" category and could do what you asked for - if only you could find it in a retail product with suitable connectors.

Another thought ... by any chance, do you have a free M.2 PCIe (not M.2 SATA) port? You could somehow make use of it.

 

[Transpanda]

PCIe switch chips do all of that. All or most of those we've mentioned in this thread do that, and AMD/Asmedia Promontory chipsets belong here too.

Actually, I'm not sure if there's a standard terminology all manufacturers use (switch vs. bridge vs. multiplexer). Probably not. But there exist at least two categories of chips, and since Asmedia makes both, I'm taking their names as an example:
- ASM1480 is a "multiplexer / demultiplexer Switch", probably not even aware of PCIe protocols, and not able to do what you asked for
- ASM2806 is a "packet switch" that can be found in the "PCIe Bridge" category and could do what you asked for - if only you could find it in a retail product with suitable connectors.

Another thought ... by any chance, do you have a free M.2 PCIe (not M.2 SATA) port? You could somehow make use of it.

Well colour me surprise, I looked into the chips/company you mentioned. Some of their chips do indeed have the functionality I need, even though their official use i slightly different.
There’s one issue though, I was only able to find pcie to sata / pcie raid cards using their chipsets. Are those chips exclusively found on motherboards or only available to organisations maybe?
If you know of any offers for something suitable, please let me know.

Unfortunately my mobo only has a singular nvme slot which is reserved by my system drive, all though it would in theory be possible to use it. (I have tiny 11 installed on an nvme with a usb 3.2 gen 2 adaptor for experiments)
I only know of nvme m.2 to full sized pcie adaptors that are x1, are there x4 versions?

Thanks for the infos ( :