Bifurcation Babylon

Wendel, please explain the madness…
After excitedly buying a new AM4 ( ASUS ROG X570 Crosshair VIII Hero) along with a 4x m.2 16x pci-e expansion card plus a bag of the cute little $15 128GB laptop nvme drives, so i could play raid games (and mebbe even ZFS on Fedora 35) I had my hopes crushed because that particular ( ~ $400 ) motherboard won’t support more than * x2 bifurcation (on a x16 slot), despite having enough lanes to do so. [cue the grumpy cat expression] Grrrrrrrrr.
Upon further research i find that what CPU you are using is also relevant, finally landing on a huge franken-spreadsheet list of what combinations work (to get 4x bifucation) on AM4. This seems like madness to me. Shouldn’t bifurcation simply be lane/bandwith limited? Am i living in a Polyanna bubble? Why must this be?

Sincerely, - your devoted hardware hoarding peon.

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There isn’t that many lanes to begin with, and PCI-E switches cost money and add complexity and latency that some folks don’t care for.

https://www.asus.com/support/FAQ/1037507/

This link above says you can get four way bifurcation, in the top slot where people typically put the GPU.

Where’s your GPU? (ie. can you get 16 lanes to that slot?)


Just checked the manual for the board, they expect you’d leave your GPU in top slot at 8 lanes and bifurcate your 8 lanes of storage in second slot to x4x4.

You have 24 lanes on your CPU, 4 go to chipset, 16 go to first two slots. … What if you used the GPU in the bottom slot?