B450 APro Max PCIE_05


New member
Mar 19, 2021
Hi guys, hoping you can help.

I have a B450 APro Max with an AM4 socket. It has 4 PCie slots for risers, and 2 PCie 16 standard slots.

For some reason the motherboard only recognizes GPU on both the PCIE 16 and 3 of the PCIE 1 slots. One slot on my MB (PCIE_5) won’t recognize any card, no matter what configuration I do.

Someone mentioned something about lanes, but I don’t fully understand. I have a SATA SSD plugged in, and from I’ve read maybe changing that will open up a lane?

is this a bios setting?

Any help would be appreciated