Area-51m R2 PCIe Training Error (Bus 3F/Slot 16)

I have two issues that I think are related:

The first is that on startup I get an error 'PCIe - Training Error PCI tag 3F00 Vendor ID... Bus 3F link degraded maxWidth x4 negWidth x2. PCIe slot 16'

Additionally the smaller power supply (180W) no longer works; but not until it is plugged into the laptop with the other power supply connected. It has power going through it and the end light is blue when it's plugged in. If it's plugged into the laptop while it's on the end will no longer be lit blue and wont be charging/passing charge.

Which connection should I be looking at to make sure it's seated properly and potentially replace if the issue persists?