While you're correct that the memory controller is now integrated into newer CPUs, it's very difficult to say which part is actually causing the failure (since it could also be some electrical issues on the motherboard itself). Given the same consistent failure addresses, I would be inclined to lean towards it being an issue with the memory controller (and thus CPU die), but I've seen stranger things happen.
Your best bet would be to either test your motherboard with another CPU to see if the issue persists, or likewise, test your CPU in another motherboard to see if the issue is replicate-able.