Like my 2009 quad core which heats up my room? Assume they have lower end graphics chips options. The power supply will be better tuned to the system since it won't need to accommodate arbitrary cards, so that might run a bit cooler. No spinners will be cooler (I'm JUST considering the pro here, not any external enclosures you might need). They won't need as much board support and miscellaneous stuff (fans). Maybe some of that power management work in Mavericks will help with the Pros.