Question Old GPU won't work in the top slot, however, newer GPU does.

[absence209]

Hi,
I have an MSI b450M Mortar, and I tried plugging in an ATI HD5450 into the top slot (the silver one, nearest CPU) and it does not boot or anything. When I switched out the GPU with a GTX1050ti, the PC started just fine. For now I have the GPU plugged into the bottom slot of the motherboard and it works, however, I would like to put it in the top slot so it can have a separate IOMMU group. Could this be a PCIE generation issue? I checked online and it says my motherboard is gen2 compatible. I tried looking through the BIOS for a setting and did not want to mess anything up. Any suggestions?

 

[Lutfij]

Welcome to the forums, newcomer!

Perhaps try and see if enabling CSM in BIOS for the motherboard and then dropping in the HD5450 works. it might not even even be PCIe gen issues, since it should be backwards compatible but you could rule that part out by manually setting the first PCIe slot to a lower generation(if it's on Auto or Gen 3).