27-inch iMac SMC Firmware Update 1.0
System Requirements:
10.6.3 or later
27-inch iMac EFI Update 1.0
File Size: 388 KB
This update fixes Target Display Mode compatibility issues on 27-inch iMac computers.
For more information about SMC firmware updates, please see this article: http://support.apple.com/kb/HT4117
For additional information, please visit: OS X Mountain Lion: Firmware updates may keep reappearing in the Mac App Store.