As mentioned above I got these from EZDIY-FAB on Amazon:
Use these and tuck the cables behind the GPU.
https://www.amazon.com/gp/product/B09PG5LDMT/ref=ppx\_yo\_dt\_b\_search\_asin\_title?ie=UTF8&th=1
Thanks!
To A:
It is the original riser cable plus the one that came with the vertical GPU mount for my Lian-Li Lancool II. Both are PCIe 3.0, and the Lian-Li one is sitting between the board and the one that came with the case. I tried using just the one from Lian-Li, but it has a 90 degree connector on the GPU side, and I couldn't find a useful way to mount that to the case without starting to drill new holes.
To B:
These adapters have names like "VGA PCIE 8 Pin U Turn 180 Degree Angle Connector Power Adapter Board", basically a small PCB with 2 power connectors soldered to it, turning the cable around so it's easier to hide them behind the GPU (especially when vertically mounted). I use one of these here:
https://www.amazon.com/dp/B09PG5LDMT
They seem solid so far, I had power splitter cables in the past that had me worrying more. But to be fair: I haven't found anything yet where it specifies the actual load you could put on them, but they are sold specifically for PCIe VGA power cables to connect, so I think it is reasonable to assume they would match the PCIe SIG specifications.
Only problem I have seen so far: make sure you get the right ones, as there are 2 variants, matching the respective way of whichever side of the GPU PCB the original connecter is located.