My iMac keeps shutting down.

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My iMac keeps shutting down.

I have a mid 2011 iMac 27" I have a second monitor hooked up to it now. I have been having this problem before the second monitor was hood up. I would be working and no warning it would just go to a black screen. The only wayto turn it on was to hold down the power button and let off then press it and it would come back on.

I had a Mac person tell me it was a bad power supply so I had that done and I hooked up a second monitor to it and the iMac will shut down and I cannot turn it back on but the second screen is still on and I am able to use it like it was the main screen with no issues.

I just spent good money on this power supply problem after doing the SMC reset with no help. At least then it wouldn't shut off every couple minutes like now.

iMac, 27" iMac intel i5

Posted on Sep 2, 2014 12:22 PM

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Answer 1

chuck_3rd

Community Specialist

Sep 4, 2014 8:08 AM in response to BenWah76

Hello BenWah76,

Thanks for using Apple Support Communities.

To troubleshoot this issue please follow the steps in the article below.

No video or no signal, image distortion, "snow," or flickering

Check connections

When using an external display be sure to check the following:

If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure. It is always good to have your notebook connected to AC power when an external display is in use.

Confirm display adapters are fully seated in their respective connections and that they are supported models and for the computer and display. Refer to these articles to assist you with adapter compatibility and further configuration information:

Monitor and Display Adapter Table

About Mini DisplayPort to HDMI adapters

Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)

Thunderbolt ports and displays: Frequently asked questions (FAQ)

Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.

Try unplugging the video adapter or cable and then plug it back in.

If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.

Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.

If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).

Reset the system

You can reset the Mac's parameter RAM and SMC.

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 Displaysfrom the View menu to open the preferences pane.

Select any resolution and refresh rate that your display supports.

Restart your computer.

If the issue persists then please follow the information below.

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

http://support.apple.com/kb/HT1573

Take care,

Alex H.

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