That's not correct, AFAIK. True, all the energy must go somewhere, but
heat is just one form of radiative energy. There are a lot of options.
It just so happens that heat is the prime mechanism of escape for this
energy in this situation. Photons are another common escape route. The
photons can then strike atoms elsewhere, getting converted into heat,
but that's not required. I'm sure given time and someone who knew lots
of physics we could give you a list of non-heat energy-loss situations.
Well, yes. A CPU radiates photons just the way an antenna would. The
CPU itself is a terrible antenna and it is effectively trapped inside
a Faraday cage, which will very quickly convert those photons to joule
heating in the very near vicinity of the CPU.
Some tiny amount of energy has to be able to make it out of the CPU in
some form other than heat in order to allow it to communicate with the
outside world. *Some* of that energy will be radiated succesfully as
photons without first being thermalized, but thanks to the
machinations of the FCC, which imagines that people still watch TV by
some means other than cable, most of those photons are trapped by a
larger effective Faraday cage which quickly converts those photons to
heat.
The energy in this particular category is not necessarily dissipated
in the direct vicinity of the CPU. They *are* converted to heat, but
they do not create a cooling problem unless you keep your laptop
running in a confined space. In any case, the amount of energy in
question is tiny.
Some photons will actually make it into the wild without being
converted to heat. The amount of energy involved is so tiny as to be
irrelevant to the discussion.
My statement as you quoted it is still literally true, but it is also
true that not all of the energy dissipated by the processor has to
contribute to the warm leg effect. Nit-picking aside, the statement
is also practically true in terms of the warm leg effect, with one
important exception.
The important exception, and one that does confuse me, is that I don't
know how to account for the energy dissipated in voltage regulation
circuitry in the immediate vicinity of the CPU. I'm sure that Intel
does not include that power dissipation in its quoted numbers, I
suspect that it is a non-negligible amount of heat, it does contribute
to the warm leg effect, and I wonder what category people would put it
into if they had to make all the means of power dissipation equal the
actual power being drawn at the DC connection of the laptop.
RM
.
