iMac EFI Firmware Update 1.1
System Requirements:
Intel-based iMac
Mac OS X 10.4.6 or later
File Size: 6.1 MB
This EFI Firmware Update fixes several Boot Camp, start up, and wake-from-sleep issues on iMac computers.
After the firmware update is successfully applied to your computer, your Boot ROM Version will be:
IM41.0055.B08 (early 2006)
IM42.0071.B03 (17-inch mid 2006)
IM52.0090.B03 (17-inch late 2006 CD)
IM51.0090.B03 (20-inch late 2006)
IM61.0093.B01 (24-inch)
You can confirm the version of the Boot ROM installed on your computer using System Profiler.
Note: Print or write down these instructions before you begin the update.
To update the firmware on your Intel-based iMac:
Quit all other open applications.
Click Shut Down in the iMac EFI Firmware Update window and wait for your computer to shut down.
Press and hold the power button on your iMac until the power indicator light flashes repeatedly, then release the power button to begin the update.
A status bar indicates the progress of the update.
Important: Do not interrupt the update.
Your computer restarts automatically when the update is completed and opens the iMac EFI Firmware Update.
Click OK, if the firmware is now up-to-date.
If these instructions appear on your screen again, the firmware update was not successful. Repeat steps 2, 3 and 4.
For more information, please visit this website: About firmware updates for Intel-based Macs.