updated 09:45 pm EDT, Thu July 28, 2011
MacBook Air 2011 uses mini Eagle Ridge chip
An investigation into the new MacBook Air's internals has revealed that Apple is using a new, relatively untested Thunderbolt chip. Nicknamed Eagle Ridge, it has two 10Gbps bidirectional lanes (40Gbps) where the Light Ridge chip in the iMac, MacBook Pro, and Mac mini has a full four. The part tracked down by AnandTech can only drive one display over Thunderbolt but is also much smaller and most likely cheaper, a key to fitting it into even the 11-inch, $999 Air.
In practice, the controller isn't significantly slower for high-speed peripherals like the Promise Pegasus R6 RAID array. Performance differences have more to do with the OS and processor than the Thunderbolt chip. Multiple devices in a chain may hit a limit, but the chip is still enough to run the multiple interfaces off of a Thunderbolt Display without being congested.
The MacBook Air is likely to be the only Mac that uses Eagle Ridge. It's speculated that Intel's more frugal design may be the choice of Windows PC builders who want to claim Thunderbolt support but want to save money. Sony's head start on most rivals for implementing the technology and might see newer PCs use as yet unannounced chips.