imac randomly blue and broken up screen

Feb 7, 2017
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my work computer randomly displays broken up blue parts of the screen as in attached image below. its a 27inch mid 2011 imac running sierra beta. i will upgrade to latest sierra next time im there but i was wondering if anyone thinks this is a hardware problem as it seems a bit too mad to be software.

the only way to make it go away is to restart the computer multiple times or just leave it off for a while and it will resolve itself.

please help if you can.




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Sep 17, 2014
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First, why are you running "sierra beta"? Sierra has been out since late September, with the latest version being V10.12.3.

Secondly, I have never "replaced" beta software with the "permanent" version, so I am unsure if any problematic stuff connected with the beta release will get properly replaced. One suspect it would, but I am certainly no expert with that (I never use beta software, and especially with an OS).

Third, a couple of things would help:

1. Have you ever done any disk cleanup/maintenance/repairs on your iMac? There are both excellent freeware and commercial products you can use to help you with that.

2. Are you making backups to an external device? That is usually always good practice, but in your case, such backups could have problematic files which are causing your grief.

I'm wondering if a clean, "virgin" installation of OS 10.12.3 is in order. You can of course get the latest version of Sierra from the App Store, but without a "reliable" backup, that process will be risky.
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