At those speeds, doesn't the cable/bus length play a huge role? What's the maximum length that can support them? I'd imagine it'd be a few centimeters at most...
Gen 3 PCIe with optical cables works up to 100 meters.
Seems strange they are using cat 6 cable, which is specified/characterized/tested to 500 MHz, at 2500 MHz for gen 2. Loss is probably not an issue because I see a redriver on the adapter card, but this doesn't seems like a robust solution. I suspect there is a lot of variation in cat 6 cable behavior (across vendors, cable, crimping) at 2.5 GHz.
shorter is obviously better, but from what I've read 30 cm PCIe riser cables work, and there are 50 cm examples.
We have problems with signal integrity on cheap risers and ribbon cables.
Huh, that's longer than I thought, thanks.
As long as the insulation is good, in theory everything is possible.
You could build your own super long PCI Extender Cable, using superconductors...
Resistive losses are only a part of the total loss on a transmission line.