iMac screen is suddenly turning white and requiring a hard reset. Why?

[iToast]

I've tried searching for a reason as to why my iMac (purchased new in October 2011) has suddenly started getting this issue.

It first occurred Sunday night, and has happened just under 10 times since. The first few times the screen would flicker as if it had a bad TV reception, followed by the entire screen going white (the boot up screen minus the apple logo). Now however, it's not giving any flicker, it will just go white without warning. Most times, but not all if I remember correctly, had YouTube running either at the front, or running in a tab whilst on a different one.

I saw somewhere online that recommended holding Command, Option, P and R before the white screen during boot up, to reset the PRAM, which I did last night. It appeared to be fixed, but then I had the screen turn white on me this morning.

Details about my 27" iMac (I can provide more if required) :
OS X - Version 10.7.3
Processor - 3.1GHz Intel Core i5
Memory - 4GB 1333 MHz DDR3

I've looked online, through various Google results, but unfortunately most people seem to get a black screen which indicates the backlight has gone. It seems like I'm getting the opposite of that. I even tried signing into Apple Support Communities but the sign-in system glitch prevents me from doing so. Top work, Apple.

Any help on this matter would be greatly appreciated.
Thank you.

 

[Bear]

...
Details about my 27" iMac (I can provide more if required) :
OS X - Version 10.7.3
Processor - 3.1GHz Intel Core i5
Memory - 4GB 1333 MHz DDR3
...

Have you thought about updating to 10.7.5 + security patch?

Did you update anything just before the issue started happening?

Is Flash up to date?

Which web browser were you using? Is that up to date? Does this problem only occur when you're using the web browser? What else do you have running at the same time when it happens?

 

[iToast]

Have you thought about updating to 10.7.5 + security patch?

Did you update anything just before the issue started happening?

Is Flash up to date?

Which web browser were you using? Is that up to date? Does this problem only occur when you're using the web browser? What else do you have running at the same time when it happens?

Thank you for the reply.

I haven't updated the OS no, to be honest I was unaware of the update.

Again no, I had actually barely used it this weekend as I was on a weekend course so left my house at 8:30am, didn't get in til about 7:30pm and only used it for about 3 hours on Saturday night. Sunday night was when I first encountered the issue, so it really is out of nowhere to me.

Flash is up to date I believe, but I will double check that. Same for my web browser, FireFox. I've been using FireFox since I got the iMac and have updated it regularly, and it's all I had running when it's happened. It hasn't happened for about an hour or so now, and part of me wants to go on YouTube to see if that's the reason for it to happen, as like I said, most times I had YouTube open.

 

[iToast]

Well, at about 3pm yesterday the OS update to 10.7.5 had finished and since then I hadn't had the issue again....until just now. Watching YouTube, then out of nowhere a white screen and no sound.

Currently doing an extended Apple Hardware Test to see if that helps. I'm not sure if I should be worried or glad that most people have their screen go black instead of white.

 

[Chupa Chupa]

If it HW test isn't positive for a defect & it happens again try booting in safe mode and observing:

http://support.apple.com/kb/HT1455?viewlocale=en_US&locale=en_US

If it still happens in safe mode back up if you don't have one and do a clean install of the OS and all your apps.

If it still happens after that its a h/w issue.

Alternatively, if the problem is easy to reproduce take the machine to the Apple Store and let the geniuses hook it up to their diagnostics. They have tools more advanced than the consumer h/w test.

 

[iToast]

The Hardware Test came back with no results.

I've got an appointment booked at my nearest Apple Store tomorrow morning so am backing up all the important files today. So far, no more white screen-ing, however I'm somewhat afraid to go on YouTube as it occurs mostly when I'm on there.

I don't get why it's happening all of a sudden either. I've been watching things on YouTube daily since I first set it up, so I don't see why it would be causing an issue.

I'd like to think it's just a loose cable on the inside, that fails when being used for video streaming or something.

 

[duchdo]

The Hardware Test came back with no results.

I've got an appointment booked at my nearest Apple Store tomorrow morning so am backing up all the important files today. So far, no more white screen-ing, however I'm somewhat afraid to go on YouTube as it occurs mostly when I'm on there.

I don't get why it's happening all of a sudden either. I've been watching things on YouTube daily since I first set it up, so I don't see why it would be causing an issue.

I'd like to think it's just a loose cable on the inside, that fails when being used for video streaming or something.

Dear Sir,

Have you figured out the problem? My iMac is doing the same as you have previously described and I haven't seen any post on google.

Thanks

 

[veracai]

had exactly same problem

The Hardware Test came back with no results.

I've got an appointment booked at my nearest Apple Store tomorrow morning so am backing up all the important files today. So far, no more white screen-ing, however I'm somewhat afraid to go on YouTube as it occurs mostly when I'm on there.

I don't get why it's happening all of a sudden either. I've been watching things on YouTube daily since I first set it up, so I don't see why it would be causing an issue.

I'd like to think it's just a loose cable on the inside, that fails when being used for video streaming or something.

I also had exactly same problem here. Goes to white screen suddenly when visit Youtube. Visit Youtube all the time and this is the first time it happens -- right after click the youtube video. MAC version is 10.6.8

 

[duchdo]

I took my to apple store. GPU faulty was diagnose. or so they said. got it replace for $180.

 

[yjchua95]

I've tried searching for a reason as to why my iMac (purchased new in October 2011) has suddenly started getting this issue.

It first occurred Sunday night, and has happened just under 10 times since. The first few times the screen would flicker as if it had a bad TV reception, followed by the entire screen going white (the boot up screen minus the apple logo). Now however, it's not giving any flicker, it will just go white without warning. Most times, but not all if I remember correctly, had YouTube running either at the front, or running in a tab whilst on a different one.

I saw somewhere online that recommended holding Command, Option, P and R before the white screen during boot up, to reset the PRAM, which I did last night. It appeared to be fixed, but then I had the screen turn white on me this morning.

Details about my 27" iMac (I can provide more if required) :
OS X - Version 10.7.3
Processor - 3.1GHz Intel Core i5
Memory - 4GB 1333 MHz DDR3

I've looked online, through various Google results, but unfortunately most people seem to get a black screen which indicates the backlight has gone. It seems like I'm getting the opposite of that. I even tried signing into Apple Support Communities but the sign-in system glitch prevents me from doing so. Top work, Apple.

Any help on this matter would be greatly appreciated.
Thank you.

Why not upgrade to Mavericks for free? Lion is a resource hog.

Yours is a 27" 2011 iMac? If you have a Radeon 6970M card, it's covered by Apple under a repair extension program because there was a known defect in this card.

 

[Babuti]

I'm having the same problem for the past month. Not much of a YouTube user. Happens after Mac goes into sleep mode. Seems like lots of guessing here but no consistent fixes.

 

[labarker]

I took my to apple store. GPU faulty was diagnose. or so they said. got it replace for $180.

Thanks for taking the trouble to post this. My screen went white this morning (all I was doing was deleting emails) forcing me to switch off the machine and reboot, and I sure hope my GPU isn't faulty. It cost me NZ$262.68 (from eBay) only 2-1/2 years ago and I hate the thought of having to replace it yet again.