According to Arstechnica, an insider source has told them that MS is preparing to introduce revisions of the core and premium version Xbox 360 units in late August or September of which will both include a HDMI port on the systems. Further to this they will feature a 65nm CPU and quieter DVD drives.

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According to my source, Microsoft wants to cut through all their existing inventory of hardware. They will then quietly "soft launch" a new version of the Core and Premium hardware in late August or September that will include an HDMI port. It's also expected that this new hardware will feature the 65nm process for the CPU and quieter DVD drives. The new hardware will ship in boxes very similar to what we saw on store shelves now, but there will be a small "call out" on the box so you know you're getting a system with the HDMI connection.