First make sure you have the latest Non-Beta BIOS Version installed.
Then check in BIOS Settings if there is a setting to change the PCIe x 16 lane to 4.0 from 3.0.
Download and run GPU-Z to verify you are running at PCIe x 16 3.0 and to see if the AMD driver is installed correctly.
According to my GPU-Z when the GPU card is in the power saving mode it will show a slow PCIe speed but once under load it will show the correct PCIe x 16 speed of 4.0
I recently upgraded my Nvidia 1070 to a 4060. My BIOS automatically changed the PCIe lane from 3.0 to 4.0.
With the previous 1070 GPU-Z showed it was running at PCIe 3.0 but now with the new GPU card it is showing running at PCIe 4.0.
So using GPU-Z start the Render Test and see if the PCIe speed changes from 3.0 to 4.0.