To a chip? Doesn't seem likely. Adding something like an Intel Management Engine is quite a task, and they'd look awful if they got caught trying it in secret.

To a chip? Doesn't seem likely. Adding something like an Intel Management Engine is quite a task, and they'd look awful if they got caught trying it in secret. If they're just making the CPU, in isolation from the rest of the system, I imagine it would be just about impossible to do something like that. As to whether such changes could be detected, given that the intended design is known, I'm not sure. Someone more knowledgeable than me might be able to comment on that.