Also, Valve's source engine is known for being relatively cpu-bound (compared to other engines).

Is it known/suspected that AMD have an equivalent?

Yes they do: https://www.reddit.com/r/security/comments/4ot223/do_amdproc...

Yes, the AMD PSP[1] chip.

[1]: http://www.amd.com/en-us/innovations/software-technologies/s...

AMD Platform Security Processor

Is there some fundamental reasons why the domain check would always succeed in a sandbox? Would this not be simple to workaround by security researchers?