EDIT: I always run latest drivers - never had a problem w/ them other than when using stak/derivatives (TRM is an entirely separate codebase, so doesn't suffer from the same issues.)  It should be noted that the latest Adrenaline drivers allow setting P0-5 now, which should remove the need for PPT.  Sadly, based on my testing it would seem they forgot to extend this capability to the mem power states, which also act as voltage floors to the core.