This is rather old and I was wondering if the information here is still valid.
I'm not sure what models it concerns, but someone recently claimed that new Mac's (not sure if they're on the market yet) have a proprietary power management chip that doesn't have autonomy (as in, it depends on software/drivers to control it and without those won't change (most importantly reduce) voltages when required (kernel-based pre-emptive micromanagement)).
He also stated the CPU itself is autonomous in this regard, so one wouldn't be hurting the CPU, but it's supporting circuitry would remain on too high a voltage and might be damaged easily.
I find it vague at best and have a hard time finding more about it. But pretty curious :)
Apparently, he's been claiming it for 8 years or so.