best way to expand and move PCI-e 4.0 slots for GPUs?


New Member
Apr 7, 2022
I have a custom built server running UnRAID. The "case" is a custom frame using 20/20 aluminum extrusion so I have a lot of freedom as far as space and configuration goes. I have 3 video cards in there right now and I am trying to figure out the best way to arrange things so the video cards are not up against each other. Here are my specs:
Mobo: Gigabyte Technology Co., Ltd. TRX40 DESIGNARE
CPU: AMD Ryzen Threadripper 3970X 32-Core @ 3700 MHz

The board is PCI-e 4.0 and it has four x16 slots, two are full x16 and the other are x8. My board supports bifurcation and I want to keep it running with PCI-e 4.0 and not have to drop down to 3.0. I've looked at bifurcation cards, splitters, extension cables, etc. I could probably use one flat ribbon cable extension to move a card and space things out but I'm concerned about the cable length issues making it drop to PCI-e 4.0. I wouldn't need a long one but I'm worried just having an extension, no matter how short, will force it to drop to 3.0.
I've gotten a lot of information from here:
and other places. With all these different connectors and how most of these are geared towards drives, I'm just not sure what kind of issues I'll come across. Will using the SAS connecters help with the cable length issues for PCI-e 4? Do they have a rediver or retimer or does SAS have something inherent for this? I haven't seem any information on that. Then there is costs of cables, cards, etc. My mobo also came with this card for m.2 drives:
I don't need the card so maybe I could use it with these?:
But again, cable length, two x8 vs four x4, will it even work, etc. Plus it looks power hungry and there are similar cards for cheap that aren't. There are just so many combinations of things I could try and things to consider. I'm hoping to be able to narrow things down a bit so I don't end up spending a bunch of time and money on this. I'd appreciate any advice. Thanks in advance.