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Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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Black screen after video card replacement.

Hi,

I bought a new video card from a reputable dealer (Macpartsonline) and followed the advice on this page iMac Intel 20" EMC 2133 and 2210 Video Card Replacement up to step 38, because the new video card had a heat sink attached. I replaced the video card unit and reversed the steps. Now when I start up the computer I hear the chime and fans whirring, but get a black screen. Is there some cable I didn't reconnect correctly?

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If you are 100% certain you put the card in correctly and all cables have good connections you probably have the wrong EFI in the computer… especially if the card is not an exact match for the one you removed.

Other possibility is wrong extension (aka driver). This one is easier to test. See if you can boot from an install disk (has more drivers - generic drivers). If so do a OS reinstall.

If this answer is acceptable please remember to return and mark it.

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8 Comments:

It's not the exact match but seller said it's compatible.

My iMac is chipset model ATI Radeon HD 2600 Pro, Processor: 2.66GHz Intel Core 2.

The card I bought is ATI Radeon HD 2600XT...

Is this a problem? Are they incompatible?

Philip

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PS: Thanks for the advice. Didn't get a chance to try booting up from the install disk last night - will try tonight. I also forgot to add that the 1st two diagnostic LEDs light up but the 3rd and 4th don't.

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Here's a tech note about EFI note its for a MacPro series. A link about the "reliability?" of that card... I wouldn't know how you can verify it's a good one.

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I tried booting from the install CD. It sounds like it is booting up, but I can't see what is happening because the screen is totally black. Again, the 3rd diagnostic LED is not lighting up, indicating the video card and computer are NOT communicating.

I figured I would put my old video card back in and endure the faulty pixelated display while I download the driver update, and then put the new video card back in.

However, after putting the old video card back in, I am now getting a black screen on start up and the 3rd LED is not lighting up...

Your first sentence was "If you are 100% certain you put the card in correctly and all cables have good connections"... I'm not so sure now... I think something is not connected right. I suspect it might be the inverter cables attached to the back of the screen.

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Step 11 of the guide is extremely vague. It says "During reassembly, the order of the inverter cables is interchangeable within each socket." Is this true? I have a feeling there is a preferable order and I've got it wrong...

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I have checked the connection to the GPU a million times now. Any thoughts as to what else this could be?

Thank you,

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Thanks Phillip and everyone else involved with this thread. I was in the same situation as Chris…about to give up after what seemed like a learning process/waste of time. You guys made it a learning process with results! I reseated my GPU for the final time, after loosening it’s mounting screws a bit first, finally retightening the screws and it finally booted up 100% once assembled. BTW, my symptoms after baking my GPU, adding new paste etc, were three diagnostic LED’s only and a completely black screen. Viva las old iMacs! Mine is a mid 2007 20” as well. Cheers to you all and the baking advice and videos.

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Philip Sneyd will be eternally grateful.
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