According to
modcontrol.com, the first wave of Xbox 360s overheated because, when
Microsoft built the machines,
it forgot to take the foil wrappers off the heatsinks. They checked on 2
independantly bought Xbox 360 consoles and found that the protective layer on
the GPU heatsink's heat transfer pad didn't get removed during assembly. The
protective layer was probably put on by the manufacturer of the heatsink to
protect the heat transfer pad from dust, before final assembly.But the failure
to remove the wrapper caused the GPU chip to sit against the plastic protection
foil, instead of the heat transfer pad.
This video(16MB) clearly shows the protective foil as they remove it.
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