Apple has just released the iMac Graphics Firmware Update 1.0. This patch updates the graphics firmware on the ATI Radeon HD 2600 PRO cards and fixes the problems which causes iMacs to lock up/freeze.

This update is only intended for 20 and 24-inch aluminum iMacs running Mac OS X 10.4.10 (Tiger) with software update 1.2.1 or the Mac OS X 10.5 (Leopard)with software update 1.3.

It was mentioned on the official Apple website that not every iMac needs this update. If you are not automatically given the option to download it, then your system does not need it. Manually downloading this patch and installing it on an ineligible computer will cause an error message to pop up. You can find more information about this patch through the Via link below.