Je crois avoir trouvé la réponse à ma question
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August 9, 2007 - Following some early rumors, it has now been confirmed that new Xbox 360 Premium consoles are hitting retail with the addition of an HDMI output. HDMI was previously a feature unique to the Xbox 360 Elite, but it would now appear that it will become a standard feature of the lower-end Premium model.
It´s likely that the HDMI-equipped Premium models are also sporting the new 65nm CPUs and additional GPU heat-sink, which should make them less prone to failure than the older design. Buyers can identify the updated Xbox 360 Premiums via HDMI-logos on the boxes. The newly lowered price of $350 will apply to the upgraded Premiums just as it did to those that came before.
From IGN.com
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Comparaison entre l´ancien Premium et le nouveau :
http://xbox360.joystiq.com/2007/08/10/spot-the-hdmi-enabled-xbox-360-premium-at-retail/
Et j´ai trouvé ça sur :
http://www.frenchconnexion.org/forums/viewtopic.php?t=6425&postdays=0&postorder=asc&start=0
Donc il semblerait que le 65nm soit aussi désormais intégré dans la version Premium et pas uniquement dans la version Halo collector de la console.