I'm not sure your new mobo causing it.
Just keep gettin code 43 on the 470 and low hash on the 580..cant figure it out.
Code 43 usually related to device hardware fails nor fails on the device driver, I'm not sure which one that was you facing. Maybe you need to try to re-flash your bios card, then reinstall the driver (
try a few drivers versions)
I tried swappin pcie slots and tried both by themselves, tried usin ddu and reinstalling the drivers.
Have you also tried using another riser?
As a standard operation for Polaris cards (
modded), in case you forgot to do this: