LCD stops imac working?

Question

Zacenator Author

Level 1

15 points

LCD stops imac working?

Hi all,

I’ve been working on a mid 2011, 27” iMac and I’m completely stumped. I’ve upgraded to the following if this helps:

NVIDIA Quattro K3100M

256GB SSD

480GB SSD

2TB HDD

20GB RAM

Intel Core i7-2600

B******D WiFi/BT Card

Before the LCD goes on, I check the diagnostic LED’s by turning on the iMac - 3 of 4 light up (4th would turn on if LCD was connected and the WiFi/BT card’s LED went green too. There is also the Apple chime.

When I install the LCD, the Mac doesn’t chime, the fans start whirring and I get one beep every 5 seconds (iMac doesn’t detect RAM even though it hasn’t moved).

I’m not 100% sure, but when I opened the iMac, I believe I only saw 2 of the 4 diagnostic LED’s on (excluding WiFi/BT card), indicating that somehow the LCD is cutting the connection to the GPU?

I have attempted a PRAM/NVRAM reset, SMC reset, taking the RAM in and out, yet nothing works. I remove the LCD and back to full green lights.

I am so confused and would appreciate any help should anyone have any ideas, thank you :)

[Edited by Moderator]

iMac 27″, macOS 12.7

Posted on Jul 21, 2025 5:17 PM

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Answer 1

rkaufmann87

Level 10

148,422 points

Jul 21, 2025 5:20 PM in response to Zacenator

Do you have a question? Your NVIDIA hack is likely the issue. This is not a GPU that was designed for that Mac which would explain why it doesn't work. You need to use the original GPU that shipped with the Mac.

However on such an ancient Mac it's not worth the time, money or resources to spend on it. It is obsolete, will not run any version of Mac OS that is close to being current. My .02.....remove the SSD and get yourself a much more up-to-date Mac.

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Answer 2

Zacenator Author

Level 1

15 points

Jul 22, 2025 1:28 AM in response to rkaufmann87

Thank you for your response! Allow me to clarify that my question is ‘is my LCD stopping my iMac from working?’ Whilst the GPU isn’t native to the iMac, I struggle to understand why it may cause the LCD to stop the iMac from working, considering that before the LCD is installed, all diagnostic lights shine green. I have invested plentiful time and a decent amount of money into this and I’m very keen to see it work, so any tips or tricks you may have would go a long way. Thank you!

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Answer 3

Jul 22, 2025 2:00 AM in response to Zacenator

Re: “I have invested plentiful time and a decent amount of money into this”

Perhaps doing that with a machine that was already 14 years old, using a GPU it was never designed to use, was not the optimal course to take?

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Answer 4

Rudegar

Level 10

179,856 points

Jul 22, 2025 7:55 AM in response to Zacenator

all electronic componants have a lifespan Understanding Mean Time to Failure for Measuring Reliability | Atlassian

if it is your gpu or the lcd panel itself which have gone to a better place is hard to tell with the info you have provided

it's an 14 years old computer

these forums are user helping other users like yourself, it's sort of going to a physical apple store and asking other customers there advice

so having an argument with people here if it should last longer is not going to be very productive to you

you can reach out to apples official support channels but it being way out of warranty that may not be much use

Get Support (apple.com)

And or

Contact - Official Apple Support

And or

Contact - How to Contact Us - Apple

or complain to their feedback channels

Product Feedback - Apple

if you google and ebay it you may be able to find a replacement lcd but it might be pricy and if it's the gpu which is dead then it will not help you much.

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Answer 5

KiltedTim

Level 10

223,944 points

Jul 22, 2025 7:58 AM in response to Zacenator

Sorry, but we really can't help you with your franken-mac.

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