iMac EFI Firmware Update 1.3
System Requirements:
Mac OS X 10.4.11 or later
Mac OS X 10.5.2 or later
File Size: 1.6MB
This update fixes several issues to improve the stability of iMac computers.
After the firmware is successfully applied to your Mac, your Boot ROM Version will be:
IM71.007A.B03
You can confirm the version of the BootROM installed on your computer using System Profiler.
To complete the firmware update process, please follow the instructions in the updater application (/Applications/Utilities/iMac EFI Firmware Update.app). The updater will launch automatically when the Installer closes.
For more information about firmware updates for Intel-based Macs, please visit: About firmware updates for Intel-based Macs
For additional information, please visit: OS X Mountain Lion: Firmware updates may keep reappearing in the Mac App Store.