Encrypted MMU were very common on enterprise hardware at one time.

Now, memory can be cryogenic spray treated (upside-down air-duster) and removed within a minute... the content can be reader dumped for key recovery. This is why systems are bolted to the floor, and locked. It buys time to armadillo a system, and lock the SMART power-cycle tamper detection.

With physical access it is almost impossible to block forensic recovery with collocated keys. TPM and IME would be illegal if they actually worked. lol =3