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Question: iMac Black screen/Sleep Mode but still running


I wanted te refer to this post : iMac Black Screen/Sleep Mode because I have the exact same problem. (but it's closed unfortunelty)

My iMac turns black everytime the graphics are a bit solicited. But somehow it still running in the background and I need to press a key several times to wake it up.

I looked quite everywhere on internet before I've found this post who describe the exact same case as me on the exact same iMac (same Graphic card, RAM...)

My iMac turns black when I'm watching a video on Vimeo.com or when I'm working in Adobe Premiere Pro or even when I'm playing video clips with QuickTime. I have the feeling that is does that everytime a H264 video file is involved.

Is anyone out there find out a solution for that ?

I did all Heferkimbo did... SMC and PRAM reset, RAM check, I forced the fan to run @ 2700 rpm all the times... but it didn't change a thing.

Thanks for your help anyway !

Posted on


Apr 2, 2018 8:56 AM in response to Rodolphe-Oldtown In response to Rodolphe-Oldtown

I posted 1 year ago similar to your problem. I thought it was the problem of HDCP content with multiple displays but it's not. Try the following and it just worked for me today.

1. Unplug the Power Cord

2. Open up the RAM cover.

3. Release the RAM

4. Start the computer without putting back the cover

5. Try watching Videos and it should work

6. Turn off the computer

7. Put the RAM back to the original position

8. Turn on the computer

9. Try watching Videos and it should work

*As soon as you put back the RAM cover, problem arises again. It must be problem with overheating. I can't watch any videos before and it works now.

Apr 2, 2018 8:56 AM

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Question: iMac Black screen/Sleep Mode but still running