band only. The Wireless and Wireless N Adapters can be used on these models to add support for the 5 GHz band (albeit the former losing support for 802.11n over 2.4 GHz) and will, in some cases, offer "... better range and bandwidth compared with the internal wireless feature ..." If this adapter is connected, the internal wireless adapter is disabled. The S and E models lack the notches for the adapter. Motherboards Microsoft avoids outright announcements of new motherboard production runs and their subsequent appearance in the market in part due to uneven distribution causing buyer's remorse and to prevent purchaser delay. However, several major (and many minor) motherboard revisions are introduced to reduce costs and to allow them to run cooler while consuming less power. Note that there is no clear divide between the appearance of motherboard revisions in retail. Due to individual stock production, distribution and rotation, it may become difficult to find specific versions. The power connectors on the back of these systems incorporate a "keying" system that will prevent plugging a (newer) lower-rated power supply into an older system (which needs more power). The keying system does, however, allow older power supplies to be connected to newer systems, as this poses no problem. The initial motherboard version was known as "Xenon" and used a 203 watt power supply, and lacked an HDMI video port. Later models had an improved GPU heatsink. The "Zephyr" revision was a redesigned motherboard adding the HANA and HDMI, but used the same 90 nm CPU as the Xenon. It did however, move to an 80 nm GPU and eDRAM, with an improved GPU heatsink. The "Falcon" incorporated a newer 65 nm CPU, and required less power so it came packaged with a 175 watt power supply. "Jasper" (released late November 2008) used both a 65 nm CPU and GPU, as well as 16, 256 or 512 MB of on-board flash memory. (This was to help run a then-recent Dashboard update. Without the addition of this internal memory, a hard disk drive or memory card is required.) The "Jasper" revision required even less power, and so the power supply was also reduced to 150 watts. The "Kronos" revision is a minor upgrade of the "Jasper", moving to a new "Kronos1" GPU with a 65 nm eDRAM, and adding a new Ring of Light/RF board called "XFreedom". Due to all dies now