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jbleisure · 08:32 AM

My 21" iMac (2006) (2.16 GHz C2D 3 GB RAM} has over the past couple of months, frozen a number of times and today the screen just whited out.

By that I mean I was working on the computer and suddenly the screen went completely white. The computer remained on but obviously there was no curser or any other image on the screen.

I shut down by holding down the on/off button and when I restarted all was fine apart from a line of pixels across the screen. (this has also appeared before a few times but disappears when I restart or login again)

It is a concern.

I have made sure I have updated my bootable (clone) back-up and also moved some key files to drop box BUT....

Is this a known problem? Any advice?

....or is it time to look at upgrading to a new shiny 27" i5?

Waragainstsleep · Mar 21, 2011, 09:28 AM

Sounds like a screen fault. Got an external display you can test with?

P · Mar 21, 2011, 09:31 AM

Anything in the log files about why the crash happened? Without knowing anything more, I would guess that it is a developing hardware fault in the GPU.

jbleisure · Mar 21, 2011, 11:03 AM

No external screen to check with and I've looked through the log files but there's nothing I can identify as causing the problem.

So it's either wait and see or wait until the iMac 27' is refreshed.

P · Mar 21, 2011, 12:26 PM

Could be overheating. If that's the white iMac model, it might be the vents in the bottom clogging up. Try cleaning them.

Waragainstsleep · Mar 22, 2011, 06:32 AM

This strikes me as one of those "I want to upgrade but my wife/girlfriend/parent/bank manager needs a better reason than I want to before they'll let me" threads.

Your LCD is hosed. Apple will charge you a price that was way over the odds when the machine was new, plus labour. Time for a new iMac.

AKcrab · Mar 22, 2011, 02:48 PM

It could also be the logic board.. Either way it's time for a new machine.

Doc HM · Mar 22, 2011, 04:12 PM

Sounds like the graphics card is hosed. Which is soldered onto the logic board. When it reaches a certain operating temp, it starts to fail. Not an uncommon fault.

New iMac I'm afraid.

leeharveyosmond · Mar 22, 2011, 08:07 PM

The flaw you have described, and a number of similar display freezes or corruptions, started happening to my 2007 iMac 2.0Ghz with ATI Radeon 2400XT display, about four times a day, usually a few minutes after waking from sleep but sometimes a few minutes after (re)boot, as soon as I upgraded from 10.6.2 to 10.6.3. After ten days I got bored, and used Time Machine to restore to 10.6.2, after which the problems went away. Until I upgraded to 10.6.4.

I have not yet seen this yet in the 24 hours or so since I upgraded from 10.6.6 to 10.6.7. I don't know whether this means the problem is fixed; I can tell that 10.6.7 included a whole new set of system extensions including those which are display device drivers.

Other failure modes beside the screen going white:
screen goes white with vertical black pinstriping
screen goes yellow with vertical black pinstriping
screen goes dark, but not black: backlight can still just be seen
screen does not update other than for mouse movement
screen does not update other than for mouse movement, with excessive pixel tearing around the mouse location

The computer remains live; if you can log in remotely on the command line with ssh, you can shut down and reboot cleanly. Otherwise, you have to hold the power key to force a reboot.

jbleisure · Mar 23, 2011, 07:53 AM

it might be the vents in the bottom clogging up. Try cleaning them.

Some of them were a little dusty, yes.

Currently the problem is not so bad that it requires a new Mac, of course I'd like one, but it will be driven by need. If the problem recurs regularly or too often then yes I will purchase....it is only 30% a finance issue.

Waragainstsleep · Mar 23, 2011, 08:42 AM

If it were overheating you should hear the fans ramp up noticeably.

Do you still have the original system discs that came with it? There should be an Apple Hardware test on one of them. Its not always conclusive and won't tell you much about the display if its faulty, but it might catch a bad GPU and its quite good and picking up faulty temperature sensors and fans. Worth a try.

jbleisure · Mar 23, 2011, 04:47 PM

Thanks, I'll see if I can find it...it should be filed away somewhere.

MacCompuFix · Mar 29, 2011, 02:21 AM

You should run Apple Hardware Test on your system.