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I am wit’s end with my iMac 24" A1225 that is stuck in a constant boot loop. The iMac start’s up and hangs at the progress bar 50% point before constantly rebooting. I think I’ve tried everything: Resetting PRAM and SMC / All the startup key options - all to no new results I’ve systematically disconnected all hardware one at a time and tried restarts - no new results. I’ve also pulled the HDD and replaced with different HD pre-loaded with El Capitan (which boots up fine on its own on my other working iMac). Running AHT shows no problems either. Video card seems fine because the display is crisp with no artifacts at start up. Thinking it must be the logic board, I’ve even replaced it with a used working board and same exact thing occurs (boot loop !&&* ) which leads me to think that it must be a kernel panic or something corrupt during start up process. I’ve also disconnected the internal HDD and booted from external HD with El Capitan preloaded and still no joy. Trying to load / reinstall with the original install disk (Snow Leopard) either hangs during startup or gets me the grey screen of death screen (drops from top to bottom) forcing a shut down. I realize I’m all over the place with this info but I’m nearer to thinking this iMac is doomed for parts. Any help will be appreciated.
Since you’ve near swapped out all the parts with no success, have you thought about the video card? I know you say you are not having any video specific issues, but it sounds like it can only boot the low level EFI functions. Although odd maybe see if you can boot an external boot camp partition.
Chris, Try starting up in Safe Mode by holding down the Shift key on start up. You seem to be hanging right about the time the video card instructions get loaded. Safe Mode will generally bypass this. If it works let me know and I can tell you the fix.
Chris, Check the attached links,instruction and guides, Good luck “I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info.” http://www.cnet.com/news/how-to-address-… https://discussions.apple.com/thread/715… https://techtalktone.wordpress.com/2013/…
Chris, Were you able to resolve your issue? I’m having the exact same issue with my 2008 iMac (EMC 2211) with the same message when I turn on the verbose mode. Thanks
Same issue on a mac mini, any luck out there yet?
I am having the same issue, except in verbose mode It Never gets past the Loading Drivers.. Loading System\Library\Caches\com.apple.kext\caches\startup\extensions.mkext… 2011 Mid iMac 21.7 inch, removed all ram, loaded 10 different sticks, 3 beeps only after “Option” startup from my Snow Leopard OEM Apple installer disk. I swapped HDD’s, everything, and won’t go into recovery, safe boot, nothing.
