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iMac EFI 1.3 slows down the desktop

Funky frank

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Hi people,


sadly I installed the new EFI 1.3 update iMacs produced in 2007, presuming I could downgrade afters. This is wrong. You cannot downgrade after a successful upgrade.


I believe Apple changed somehow the speed step table of the Intel Core 2 Duo. The performance is really degraded now, for example resizing windows in the Finder causes a lot of stuttering. I use Leopard 10.5.2.


Is the an unofficial way to dump the old EFI again? In the Bios-Update.app exists an firmware file. Also on the restoration CD 1.6 there is the old firmware file available. Could it work if you replace the new firmware file with the old one and somehow simulate to the firmware update tool, still an old version is installed?


How can I downgrade the EFI firmware to the version of restoration cd 1.6?


Thank you for help.

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No, sadly Apple restricts restoration only for computers on which the firmware upgrade failed. There is no way to use the restoration cd after a successful update.


I think Apple changed the speedstep table, especially the idle speed, so the normal desktop performance is perceptible lower. It's really sad.


My question is: Does anybody here know how I could modify the 1.3 firmware updater, so it would dump then old 1.2 efi firmware instead?

The 1.2 efi firmware is available on the restoration cd 1.6. The tool that prepares the update available within the 1.3 updater:


1.3 updater:



restoration cd:



Thanks for help.

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