M'y iMac 27 inch (end 2009) won't boot with a IOPlatformExpert.cpp:1504 error , after a graphic crash

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M'y iMac 27 inch (end 2009) won't boot with a IOPlatformExpert.cpp:1504 error , after a graphic crash

Hello everybody. First i'm french and my english is so bad, excuse me for my language !

Ok i've got a iMac 27" buy in the end of 2009, with ATI Radeon HD 4850. I'm photographer and i use this mac for Lightroom and Photoshop first. I never have any problem with this mac but last week, during my work, my screen freeze. I restart with force the machine, and after the logo apple, many strange pixel and vertical straigt white and grey. You can look a capture at this link (https://www.dropbox.com/s/g45a6act347j7u0/photo2.JPG).

So i restart my mac and i try all solution and the boot : C touch, D, Option, NVRAM, verbose, single ... always freeze with the strang pixel. The only way who work is the Shift touch : Mac OS X Mountain Lion started but so slowly and with graphic acceleration problem, no video youtube, no flash on the web.

So i did my backup with tome machine and i wanted to reinstall the OS ... but the Option touch at start up don't work ... i try the cmd+R command and it work !!! Mac OS Mountain Lion downloaded, installed and my iMac work !!!!! Yeahhhhhh ! Everything works .... one day !!!! On my facebook page, the bug come back, screen freeze. I sream a lot, and i restart by force the iMac and now, the big problem ...

Everytime i restart my iMac, when the apple appears ... some line of code appears and talk about kernel and driver. I take a photo of this message at this link : https://www.dropbox.com/s/mfbb5q5p93neirt/photo1.JPG

I tried everything i know and every couple of touch at startup : C, D, cmd + R, cmd+option+R+P, option, T, S ... i'm lost in this problem, i can't reinstall the OS like the first bug, i can't enter in the single mode, i can't boot on a usb key or a Dvd, i can't use the target mode in order to repair or format the hdd ... I am in the world of apple since 9 year, and it's the first time i have got a problem with the apple device.

After reading and search on french discussions, some guys say to me that it's maybe a graphic card problem, or a RAM problem .... i don't want to bring my mac in a store cause i don't have enough money .... i am freeze, like my iMac, and i can't work the wedding photo !!!!

Maybe someone can help me ? And please, use an english very easy for me, i don't speak english since the school !!!!

Thank you evertbody.

Sebastien, Toulon, France.

iMac (27-inch Late 2009), OS X Mountain Lion (10.8.4)

Posted on Aug 31, 2013 9:42 AM

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Answer 1

Sep 6, 2013 9:27 AM in response to sebastienchenal

So, some news ! I finally format the HD by the disk target mode with an other iMac. After formating, booting from a USB key to install Mac OS X Mountain Lion: Install Mac OS X Lion Mountain successful the computer starts correctly , without display bug , no lag , no loss of fluidity ... In short, I think I have solved the problem. But after a few minutes of use , the screen is frozen , the machine is blocked , the computer no longer met again. And after a forced reboot , I end up with the same lock screen with colored pixels and vertical lines (photo this screen: https://www.dropbox.com/s/7qvv8fobjpstf8t/ecran_complet.JPG , photo zoom here : https://www.dropbox.com/s/wyvsoog79jkg8fq/zoom_ecran_complet.JPG).

After going through some forums , it seems that this is my ATI Radeon HD 4850 that is failing. Is it your diagnosis? What will be the budget required to repair an Apple Store? Can I expect Apple a gesture of goodwill (purchase or repair) , knowing that my iMac is covered by any warranty ?

Cordially, thanks a lot for your answer, maybe one !!!!

Sébastien

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