Screen stays dark -- 24" Intel iMac early 2008

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Level 1

12 points

Screen stays dark -- 24" Intel iMac early 2008

Monitor stays dark all the time, but computer powers on normally, and caps lock key lights up. If I start up normally, it will restart itself every 60 seconds. If I start in safe mode (shift key at startup) it won't restate itself. Fan and hard drive sound normal.

I've tried resetting PRAM three times and taking the power cable out three times. I let it cool down for four hours.

Everything was fine yesterday. I think the last app I used was silverlight. It went to sleep overnight, and the display just never woke up in the morning. How can I force the display to wake up?

The box says it came with NVIDIA GeForce 8800 GS graphics processor.

iMac8,1, Mac OS X (10.6.4), 2GB RAM / 3.06 GHz Intel Core 2 Duo

Posted on Mar 3, 2015 5:27 PM

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Answer 1

chuck_3rd

Community Specialist

Mar 5, 2015 10:22 AM in response to gracieola

Hi gracieola,

If you have already reset your PRAM and SMC in attempt to resolve this issue where your iMac's screen is black, then the last step before reaching out for further support or service is to boot into safe mode.

Reset the resolution

Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:

Start up in Safe Mode.

From the Apple () menu, choose System Preferences.

Choose Displays from the View menu to open the preferences pane.

Select any resolution and refresh rate that your display supports.

Restart your computer.

If you tried all of these steps for your display and the video issues persist, contact Apple technical support or take your Apple computer to the nearest Apple Store or Apple Authorized Service Provider (AASP) for diagnosis. If you plan to visit an Apple Retail Store, make a reservation at the Genius Bar using http://www.apple.com/retail/geniusbar/ (available in some countries only).

Note: Diagnostic fees may apply for issues not covered under warranty or the AppleCare Protection Plan (APP).

Apple computers: Troubleshooting issues with video on internal or external displays - Apple Support

Take care,

Alex H.

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Answer 2

gracieola Author

Level 1

12 points

Mar 10, 2015 7:46 PM in response to chuck_3rd

I took it to the Apple Store but they can't replace hardware on a 7-year old computer. They recommended third party replacement of the graphics card, but I think I'm going to try it myself. They weren't sure why it restarts itself unless it's started in safe mode. That was a puzzler. The external monitor they tried didn't work.

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