screen flicker after upgrade to os x el Capitan

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Level 1

8 points

screen flicker after upgrade to os x el Capitan

Hi All,This morning I downloaded a security update for el Capitan and my I MAC would not boot just kept hanging on the white screen,then after trying various things to try and get it going again I had to do a re install of the operating system that took forever,after eventually getting the system to boot it now it runs really slow and when using chrome as a browser the screen has terrible flickering.Does anyone else have or had this problem? and know how to fix this?.

Thanks in advance.

Bob

iMac (27-inch Mid 2011), running El Capitan very slow

Posted on Aug 2, 2016 1:30 AM

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Answer 1

tim_135

Community Specialist

Aug 3, 2016 1:12 AM in response to longboardbob

Hello longboardbob,

Thank you for using Apple Support Communities.

I understand from your post that after updating your iMac to OS X El Capitan that your iMac would not start up correctly. To help resolve this you reinstalled the operating system, but the iMac is still slow to start up and use. I know how important it is for you to be able to use your iMac smoothly without the screen flickering and being slow.

After reinstalling the OS did you restore a Time Machine backup file? If so, you may want to test the issue in a new user account to see if the issue persists or not. This article has the steps on how to create a new user account for you to use to test the issue:

How to test an issue in another user account on your Mac

Also, you may also want to restart your iMac into Safe Mode to see if the issue persists. Safe Mode eliminates any 3rd party software that may be contributing to the issue. After testing in Safe Mode restart your iMac as normal and see if the issue still persists. Use the steps in the following article to restart your iMac into Safe Mode:

Safe Mode

Best Regards

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Answer 2

longboardbob Author

Level 1

8 points

Aug 3, 2016 1:21 AM in response to tim_135

HI,thanks for the reply,after a bit of deliberation I shut down and restarted my IMac and the problem was resolved it's now working ok.

Just a quick note though, I have made a backup just in case it happens again and hopefully that will prevent me having to download and reinstall the whole operating system which took almost 3 hours,Is it possible to keep a copy of the operating system on a portable hard drive or memory stick for reinstalling the operating systemthanks agai.

Bob.

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Answer 3

Corrie84

Community Specialist

Aug 3, 2016 11:51 AM in response to longboardbob

Hi longboardbob!

Glad to hear that restarting your iMac resolved the issue for you. To answer your question, yes, you can create a bootable installer for OS X. The steps in the following article are advanced steps and are intended primarily for system administrators and others who are familiar with the command line.

Create a bootable installer for OS X

Cheers

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