x370 Gaming pro carbon, PCI-E2 won't boot to post on some cards?

[Ivan88050]

I recently purchased a MSI X370 gaming pro carbon motherboard for my Ryzen 1700X. The first motherboard wouldn't boot to post no matter what I did. Therefore, I got an exchange and received my 2nd MSI X370 gaming pro carbon motherboard. However, the motherboard wouldn't boot to post when I am using my MSI GTX 970 graphics card inserted in the PCI-E2 (x16) slot . The GTX 970 would only boot if I was using the lower PCI-E4 (x8) slot (the 2nd full pci-e slot from the top). I made sure to test my GTX 970 on my 2 other Intel rigs and using the x16 PCI-E slots and the GTX 970 would boot with no problems. Here is the strange part, my MSI GTX 1070 boots fine on my MSI X370 gaming pro carbon motherboard in the PCI-E2 (x16) slot.

I made sure I updated my motherboard to the latest bios. I have a 850w Gold certified power supply

So what is broken? I've never had this happen building PCs before.

Do you think this a compatibility issue or am I missing something.

Thank anyone who could offer me some advice or explanation.

[jklaw90]

Hey Ivan were you able to boot the board ever with the 970 in the first two slots?

i have the exact same issue....