Download Firmware Apple iMac EFI 1.1

For its entire line of Intel iMacs, Apple has released a new version of the Extensible Firmware Interface made available, which fixes some bugs related to Boot Camp and iMac startup. The new-fangled EFI is provided with version numbering 1.1 and can be accessed by clicking on this url downloaded as a dmg file. What exactly changes version 1.1 can be read below:

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″ Mid 2006)
IM52.0090.B03 (17″ Late 2006 CD)
IM51.0090.B03 (20″ Late 2006)
IM61.0093.B01 (24″)

You can confirm the version of the Boot ROM installed on your computer using System Profiler.[break]