David Smith


Screen has green and pink lines and "snow"?


Screen has green and pink lines and "snow". When it boots to the apple logo it will have green and pink lines down it and IF it boots past that none of the applications will show up it will just be a blank blue screen or desktop with the pink and green snow and eventually it will go out. What do I need to do to fix this, what parts and what tools do I need? Thank you so much for your help!

Edited by: mayer ( ) , oldturkey03 ( )

Just for clarification, it is a 27" iMac Late 2009 i5 2.66 GHz, 1 TB Harddrive.

David Smith,

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David, what Dan is trying to do, is to determine if it is your video card/circuit or your LCD. So the best and quickest way is by attaching an external monitor. Here is what Apple says about your symptoms:"

Quick Check

Symptoms Quick Check

Vertical/Horizontal Lines

• Vertical lines

• Horizontal lines

1. Boot from install DVD to determine if potential software issue exists.

2. Verify if issue is visible on an external display.

Deep Dive

1. Boot from Install DVD and verify if issue is still visible:

• Flickering image

• Horizontal bands of static intermittently appear

• Dock and / or menu bar shift positions

• Display intermittently flashes on / off

Yes--> Go to Flickering issue, go to Noise / Unstable Flickering.

No--> Issue likely caused by software or driver issue. Troubleshoot for software

issues. Make sure all software updates have been installed.

2. Verify if issue is visible on an external display attached to mini DisplayPort.

Yes--> Issue NOT caused by internal LCD. For systems with a video card, go to step 3. For systems without a video card, go to step 4.

No--> Go to step 6.

3. If a video card is present, remove video card and inspect connector for damage or corrosion then reinstall. Verify if issue still occurs.

Yes--> Replace video card.

No--> Issue likely caused by poor video card connection.

4. For systems without video card,horizontal lines may be related to a failing RAM module. Verify if video issue only happens AFTER Apple logo and spinning wheel appear.

Yes--> Issue only happens AFTER Apple logo and spinning wheel appear. Go to step 5.

No--> Issue present before Apple logo and spinning wheel appear. Go to step 8.

5. Start with shift key down (safe mode) to disable system extensions. Verify if issue still

happens when booting in safe mode.

Yes--> Go to step 8.

No--> No video issue when booting in safe mode. Go to step 6.

6. Isolate with only one memory module installed, then with the other one. Test with knowngood

memory. Verify if issue only happens with specific RAM module(s).

Yes--> Replace affected RAM module.

No--> Go to step 7.

7. Isolate with one known-good memory module installed in one memory slot. Repeat by testing in other memory slots Verify if issue only happens with specific memory slot of logic board.

Yes--> Replace logic board and retest.

No--> Go to step 8.

8. Disconnect DisplayPort cable between LCD display and logic board, and verify if there is damage to cable or connectors.Repeat with vertical sync cable connected between LCD panel and LED backlight board.

Yes--> Replace DisplayPort cable and vertical sync cable or any other damaged part/module.

Go to step 9.

No--> Reinstall DisplayPort cable and vertical sync cable.

Go to step 9.

9. Verify if issue is still present after reinstalling internal DisplayPort cable and vertical sync cable.

Yes--> Replace logic board. If video card was present, reinstall original video card.

Go to step 10.

No--> Issue resolved.

10. Verify if issue is still present with replacement logic board installed.

Yes--> Go to step 11.

No--> Issue resolved.

11. Reinstall original logic board and verify if issue is still present with original logic board reinstalled.

Yes--> Replace LCD panel. Run Apple Service Display Utility.to verify the resolution of intermittent display flickering symptoms.

No--> Issue resolved. If a video card was present, reinstall original video card."

So, I strongly advice that you follow Dan's way of doing things. Good luck.

Thanks OT! ;-}


Where can i get the GPU and Display? I have the money and would just rather go ahead and replace both of them.

David Smith,

For a proper identification you really should give us the last three of your serial number. I still think you should follow Dan's advice, there might be no reason to replace all of it at once. After all, you are looking at around $600 for parts alone. According to the manual, the video card used is a ATI Radeon HD 4670, 256MB part number 661-5314. The LCD assembly has the part number 661-5527. As for where you can get it, that depends on where you are located.


Alright, I hooked the iMac up to an external display and nothing would show up, like I said half of the time, the desktop will not even show up. And I could not do anything on the mac to try to fix this issue. The last three of the serial are: 5PJ. If I need to replace anything, the harddrive, the GPU, or the display, I will need a link as to where to find them, because I live somewhere where we don't have many computer repair places.

David Smith,

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David - It sounds like either the display or GPU is failing. To help isolate out which can you connect an external monitor to your system. Does the display on it look OK? If it does then you know the display is having problems otherwise the GPU. Let us know what you find out.

As to the needed tools the iFixIt tool kit should meet your needs here Pro Tech Toolkit and a set of suction cups Heavy Duty Suction Cups and lastly, an ESD mat & wrist strap Anti Static Mat

Product Image

Heavy-Duty Suction Cups (Pair)

Two 2.25" diameter suction cups used for lifting display glass off Aluminum iMacs. A must-have tool when repairing or replacing broken, cracked, or shattered iMac screens. — 50+ available at 14.95 each.

Product Image

Anti-Static Mat

Ground yourself and your work surface to prevent damage from electrostatic discharge (ESD). Various sizes to fit any work station: 12" x 20", 20" x 24", 24" x 48". Be ESD-safe! — 50+ available at 24.95 each.

Product Image

Pro Tech Toolkit

The industry standard for electronics and computer repair technicians and businesses. All the tools needed to repair iPhones, iPads, smartphones, tablets, Mac laptops, PCs, and video game consoles. — 50+ available at 64.95 each.

Edited by: Dan ( )

Where could I get the display or GPU from? I would rather buy them separately and repair it myself than to take it to apple. I am unable to hook it up to an external monitor at this time.

David Smith,

Well the display looks fine, I have already taken off the cover and the screen itself seems to be fine so where and how can I replace the GPU?

David Smith,

So you connected an external monitor to your system so see if that display worked Vs your internal one. If you did was it showing your desktop and the icons you would see on your internal?


OK - So the External monitor does not show anything when the internal display goes out (when the internal IS working the external also is working but is showing the same green & pink stripes). That means the GPU is gone. You can follow this guide on how to replace it GPU Upgrade.


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my screen has vertical lines too I tried ever single on of those techniques and still the white screen and/or the lines on the display screen remains. There doesn't seem to be a solution I'm sure something has to be replace. I have an apple store appt I will let you know what they say and how much it cost. I'm sure it's going to be expensive.

Edited by: Mike ( )

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