Do I need a new board?

HI … I am running a small rig with 1 rx580 and 1 5600xt. I have a third card (rx580) but when I attach it to the rig, it will not hash. if i attach it alone, hashes fine.
Here’s my question… Am I using the wrong motherboard or do i need to monkey with some BIOS setting?
I am using:

  • ASRock B365M Pro 4-F
  • 8gb of DDR 4.
    the board has 2 PCI-E x16 slots, and 1 PCI-E x1 slot.
    Currently, the rx580 is in the x16 slot closest to the CPU, the 5600xt is in the x1 slot.
    Any card I put in the second x16 slot won’t hash.
    Any thoughts on how to rectify this?
    thanks for any help…