DISREGARD!
Nintendo trick fixed my issue.
For the curious though, some fine dust in the PCI-E slot was causing the link speed on my old mATX P55 mobo from EVGA to drop to x4, when it should be at x8. Blew out the dust on both the GPU and the slot with a manual air duster (like the ones used for camera lenses) and it returned to x8 link speed.
I did knock a DIMM channel reaching for the back tab of the PCI-E slot, so it wasn’t making full contact and that was giving me grief, until I reseated the RAM.