Intel 1U NVME Backplane Question

[T_Minus]

I've got an Intel 1U backplane that does 8x SAS3 or 4x SAS3 and 4x NVME.

The manual shows both cables at once going from onboard sas3 or mezz sas3 hba to backplane, so in total we have 4x NVME cables and 2x SAS3 cables connected.

My question is, if I don't plug the SAS3 HBA cable into the NVME ports yet I only use 2x NVME can I use the other 2 ports for SAS3 or will I need all cables?

Basically, wondering if the NVME HBA can also be a SAS3 HBA or no, that's why 6 cables at once are needed.

 

[T_Minus]

Well that was fun. Proxmox install onto SAS3 dries worked, reboot but goes to uefi shell, no other options in bios to boot from ?!