I have a Crosshair X670E Extreme motherboard. I wanted to add additional m.2 ssd and noticed on the user manual that PCIEX16_1 would run X8 when M.2_2 enabled while there was no reference to GEN-Z.2. So I installed 2 SN850X 4T on the GEN-Z.2, only to find my graphic card running at PCIe ×8. Did I configure something wrong or every m.2 ssd installed after the first one reduces PCIEX16_1 lane width?
I unplugged GEN-Z.2 and found my GPU still running at 4.0 ×8, guess I had been running at ×8 all the time. I had been using M.2_1 for my only ssd and PCIE×16_1 for my GPU with a PCIe 4.0 ×16 riser cable, which should not have reduced the bandwith.
does the GPU operate at 16x when plugged in directly? Riser cables can sometimes be temperamental, always best to remove them from the system entirely if troubleshooting.