So here is the situation... I came home from work one day and my iMac would not turn on, no chime, no fans, nothing. It had stormed earlier that day so I was wondering if something tragic happened.

This machine is obviously out of warranty so I gave no thought into taking it into Apple. I've worked on many computers before but never an iMac but figured how hard could it be.

Never the less... I decided to check out the power supply. I opened it all up and while the display was disconnected from the machine I decided to give it one last power up before I proceed... Sure enough, I hear the boot chime and fans kick on. Greaaaaattt.. So I shut it down, unplug it, and reattach the display... then fire it back up... and the display looks normal, well, except for it being whitish and having distortion in the screen... like light noise... then when it gets booted it has some weird funky colors around certain elements like buttons and things... so now I'm assuming it's a graphics driver issue or some sort of graphics hardware bug...

Now... I've figured out how to reproduce the glitch, checkout the video.

1.) turn on machine and wait for the login screen. (it's white-ish and funky)
2.) click the power button which puts it to sleep or hibernates it.
3.) click the power button again and the display is fine, nice and pretty again!

It does not stay pretty after a reboot you have to do the same steps.

See attached video: http://www.youtube.com/watch?v=z10qrbzZOMo

Here is my question:


Standard troubleshooting procedure:

  • Reset PRAM
  • Reset SMC (more likely to be the fix imo, since power state changes helped resolve the problem)
  • Skillful hit with fists of rage
  • Thank you! PRAM actually fixed it. So simple, not worth even taking it apart... – Joshua F. Rountree Jul 26 '12 at 14:23
  • Same problem here and used your fix now for about a year.....EVERY TIME i open the mac. As of today 3/5/15 the "fix" won't work, I'm typing on a flashing pink color noise screen. I 've put it to sleep several times, restarted and put to sleep....nothing. Any suggestions?? – user117040 Mar 5 '15 at 15:48
  • That implies interference on the display signal lines. Are you sure the connector is well seated? – Alexander Mar 5 '15 at 16:32

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