Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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Diagnose Display or Video problem?

iMac Intel 27" A1312 EMC 2374 i7

iMac powers on and chime sounds, the display can be seen to power on and remains black the entire time, checked with flashlight and nothing is seen.

All of the LED's are lit, I can connect to the unit remotely and share the screen, I checked the system profiler and find that the video card is detected. I find that if I go to the display preferences and adjust the screen brightness you can see the backlight adjust as its supposed to.

I tried reset all settings

I tried re-seating the video card

I tried swapping backlight inverter and LCD with Known good hardware same result

video card is my last step but i just wanted any suggestions before i shell out the cash


Answered! View the answer I have this problem too

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Just an update, after re-checking all cables and connectors I found V-Sync LCD Cable broken in half hidden under the tape, I ordered the replacement and will update when I replace it.

(And yes it seems I always end up with video issues even after upgrading...gave the 20" to dad:-) ).


I replaced the cable and still get the same result here is what the system report tells me...I will try any other suggestions, otherwise I will roll the dice and order a replacement video card.

Chipset Model: ATI Radeon HD 4850

Type: GPU

Bus: PCIe

PCIe Lane Width: x16

VRAM (Total): 512 MB

Vendor: ATI (0x1002)

Device ID: 0x944a

Revision ID: 0x0000

ROM Revision: 113-B9110C-425

EFI Driver Version: 01.00.383



Display Type: LCD

Resolution: 2560 x 1440

Pixel Depth: 32-Bit Color (ARGB8888)

Main Display: Yes

Mirror: Off

Online: Yes

Built-In: Yes

Connection Type: DisplayPort


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3 Answers

Chosen Solution

If the last four figures of your serial number are one of these, then Apple will fix it for free: DHJQ, DHJW, DL8Q, DNGH, DNJ9, or DMW8


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You don't seem to have much luck with video problems. I take it you replaced your 20" iMac that you replaced the video card on ;-)


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connect it to a tv and see if you have fully working unit.

if so it is either a fried video graphic part. look it up on ebay they sell them on there because they have a ISSUE with that happening. i would take it to A APPLE STORE AND LET A GENUIS BAR WIZARD TRY AND fix it for free, he might have a used part he will give you. and there you will get a forsure diagnosis

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Hi, I connected to a Tv and worked perfect.

What part should I change to fix it?


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There is a Quality Program with regards to this model year. However, a test has to be completed by a technician in order to validate the machine. There are two different cards for this model. Only the one card is affected. Did you try external video to see if its in fact the card?

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What are the part numbers on the good and bad boards?


Don't have those as of yet. This is a new program. I have only run into one issue thus far.


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junvaz will be eternally grateful.
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