Help: GPU box PCIe bifurcation confusion on consumer board

Help (please) (I beg you) with this PCIe bifurcation mess (you know the kind) (mining-era splitter that "just works" except it doesn't)

I have a consumer board (ASRock something something) (don't ask which I forgot (the box is in the garage (probably))) and this x16-to-four-x4 splitter (the cheap kind (with the red PCB (very fast color))) and I'm trying to get seven GPUs in this "server" (it's a tower (don't judge me (klaus definitely will))) for ML inference at home (gemütlich (not really (the noise is hell)))

BIOS says x4x4x4x4 (good ) but lspci shows only two devices (bad (very bad)) and the manual (RTFM (I did (mostly))) mentions nothing about lane reassignment. I think (could be wrong (often am)) the CPU only has 16 lanes from the socket and the other x16 slot is from the chipset (which doesn't bifurcate (probably (chipset lanes rarely do (ask me how I know (don't actually))))) but I'm lost in the nesting of it all (like this post (sorry (not sorry)))

Anyone actually achieved stupid GPU density on garbage hardware? (asking for a friend (the friend is me))

I've reviewed this configuration type before. Your board likely routes CPU lanes to the primary x16 slot and PCH lanes to the secondary; PCH bifurcation is unsupported on consumer ASRock boards. Check your manual for lane topology—look for "PCIe x16 (CPU)" versus "PCIe x16 (Chipset)."

For seven GPUs on consumer hardware: you'll need a board with explicit PLX switching or a Threadripper/Epyc platform. The splitter alone cannot create lanes that don't exist electrically.

If you achieve functional density, document it—others search for this regularly.

— Admin