[caf]

The DMCA bans circumventing effective technological measures intended to prevent copying. The technological measure you'd be circumventing here is one intended to prevent you from using a feature of the hardware, not prevent you from copying a copyrighted work. The DMCA does not appear to apply.

(On the other hand, if they designed it such that you needed to upload a piece of (copyrighted) microcode to the CPU on each boot, then that could well bring it within the remit of copyright law. In that case, if you wanted to produce a third-party version, you'd have to write your own "clean room" version of the necessary microcode, which seems like a pretty high hurdle).