Model A1225 / Mid 2007 and Early 2008 / 2.4, 2.8, or 3.06 GHz Core 2 Duo processor

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videocard or LCD screen dead?


I recently encountered a black screen and now my Imac won't work anymore. (I get the Apple sound at start-up, Without the RAM is gives the beeps, no weird noises, fans are running fine).

I checked the led's and only the 4th doesn't work (which indicates a problem with the LCD).

So I ordered a mini-dvi cable to 'attach' another screen to the computer, nothing..... While the 3rd led is working which indicates the videocard is working.

What could be my problem now? I'm a little confused. ;)

Answered! View the answer I have this problem too

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1 Answer

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Try shining a flashlight into the display at a sharp angle do you see your desktop? If you do you know your screen is working but the backlight services has a problem. If you don't see an image then your GPU board is having a problem and will need replacing.

While your test implies the GPU board is having problems, I've seen some setups not work. Do you have a working system to test the cable & monitor out?

Here's a better set of IFIXIT guides to work off of: 24" iMac

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Whoohoooooo! My Imac is back online!! :) The flashlight trick didn't work. With the external screen trick failed I presumed it had to be the gpu.

Found the 'oven' trick on the net and decided I could loose nothing. 10 minutes 200 degr. C and new thermal paste. Everything back together and she's working again!!! I'm so happy! :D

Downloading SMC fancontrol for better cooling now.

Me happy happy happy!!!!!!


Well at least you know the grahics board at some point will need replacing. While the oven trick worked for now it likely won't last :-( start saving your pennies for a new system or think about replacing the graphics board.


I have a mid 2010 27' iMac that I use a lot, and last week my HD5750 GPU died : black screen, everything else working normally (I can access my iMac through shared screen with my MacBook Pro). Not a backlighting problem : no monitor on system preferences, "unknown GPU" on system report, Novabench can't run any graphics test.

I accepted that my GPU died, and searched eBay to buy another one, but it's much too expensive (400$) for a 6 year old computer. I was about to declare my iMac dead (it just got "vintage" on Mactracker), but wanted to "see" what went wrong.

So I ordered ifixit repair tools and opened my iMac yesterday : so much dust, just unbelievable. I removed the graphics card, inspected it, cleaned it (I also cleaned everything I could access in my iMac). Then I put everything back in place.

BINGO !!! My graphics card works again. And my fans don't spin fast anymore, I can't even hear them.

Just to let know a "dead" GPU may only need some dusting.


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michiel will be eternally grateful.
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