iMac EFI Firmware Update 1.2
This update improves the performance and reliability of Intel Core 2 Duo processors and fixes issues with Boot Camp for iMac computers.
After the firmware is successfully applied to your computer, your BootROM Version will be one of the following:
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