iMac 27 screen goes black

I have a late 2009 27 inch iMac and over the last 2 weeks the screen has gone black 3 times now .. Twice I was PP photos in Lightroom 5 so I thought it was maybe working hard and possibly a heat issue . Today it did it again and I wasn't working it at all, I put my hand on the top of it when it did it today and the it was barely warm to the touch .. When it does it I tried everything I could think of to get the screen back on "esc" and button combos etc. but I ended up holding the power button on a few seconds until it shuts down .. after it sits a while it works again and may work again for days ..

It's difficult to trouble shoot intermittent problems. First, I would suggest downloading the free iStat Pro and monitor the three fan speeds and temperatures. Normally, an iMac runs cool because of the way it's designed. Your problem (blackouts) may be related to a problem with the graphics card. And I believe the graphics card in your particular model iMac is replaceable as a separate unit rather than replacing the entire logic board.

Totally agree with chscag. It's tough to troubleshoot intermittent issues.

- Nick

I have been having the same problem on my late 2010 27" iMac and have been researching fixes for a few weeks now. For some replacing the graphics card works, but not all. Quite a few people have mentioned that switching from a plugin keyboard back to the wifi keyboard that came with their 27" has worked. I haven’t tried that yet as I need the 10 key keypad that comes with my apple keyboard.

My screen becomes extremely hot to the touch. I downloaded SMU Fan Control and maybe see a small difference with running that program along with directing a small fan toward the upper left back of my computer. It will work fine for 2 days, then go out randomly for the next 2. The screen seems to go black more when first starting up, sometimes up to 10 times. It is currently set to never go to sleep, but when it does go black, putting it to sleep with alt-command-eject, then waking up with space bar works almost every time for me. I have resorted to saving my work often and having my laptop on nearby with Back to My Mac running for when I can't 'wake' the screen up. Have an appointment at the Apple store this weekend, but I'm not too hopeful.

Is it too late to try the usual fixes when something odd is happening to your Mac like resetting NVRAM/PRAM, running Repair Disk Permissions in Disk Utilities, removing large file count from your desktop etc etc ?

Just returned from the Apple store - they are running diagnostics - may be the logic board or the cable connecting it. $50 if it is the cable, $700 if it is the logic board. How do I decide if it is worth it to pay $700 to repair a 5 year old iMac?

How do I decide if it is worth it to pay $700 to repair a 5 year old iMac?

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I can't advise you what to do, however, if it were my 2009 iMac I would forego the repair and put the $700 toward a new iMac. And then try to sell the 2009 machine on eBay for parts.

Second chscag's suggestion. I would sell it as is advertise fault, and putting that and the $700 towards a newer machine. Don't forget to look at Apple Refurbished if you go this way.

Thank You both for your input. I have used my iMac what I would consider heavily. I'm leaning toward a new iMac if the logic board needs replaced. I haven't heard from Apple repair yet.

I'm a little concerned that if I were to replace it it may not fix the black screen problem, or in your opinion, is it a sure thing (or at least a 99% sure) that a new logic board would override the black screen problem?

iMac screen randomly goes black

dmunroe said:

I have a late 2009 27 inch iMac and over the last 2 weeks the screen has gone black 3 times now .. Twice I was PP photos in Lightroom 5 so I thought it was maybe working hard and possibly a heat issue . Today it did it again and I wasn't working it at all, I put my hand on the top of it when it did it today and the it was barely warm to the touch .. When it does it I tried everything I could think of to get the screen back on "esc" and button combos etc. but I ended up holding the power button on a few seconds until it shuts down .. after it sits a while it works again and may work again for days ..

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"I too have have a late 2009 27 inch iMac and have experienced this 'screen blacking' (only since upgrading to Sierra iOS). It seems to happen more frequently if the computer has been in use for several hours. Sometimes it resolves by a short dab on the power button but occasionally this doesn't work and I have to power shutdown. Im sure its not a heat issue because when the power button "fix" works it restores immediately and then seems fine.
I also have an occasional issue with it waking up after being in sleep mode - sometimes it won't!

Any inside would be gratefully received but please keep the tech simple as I am a Mac-novice.

I can only add from my experience. Your late 2009 is now a year and a half older than mine was in May 2015. It needed a new board for $700 or so to repair. I have a home business and didn't want to spend the time hunting for a board that maybe my husband or a tekkie friend could install for me, so I bought a new 27" Retina 5k and am so glad I did! My husband's late 2009 27" still works fine, but he is not on his all day everyday as I used mine.
I do recommend making your decision sooner than later as I had to transfer my data from my old 27" with a screen that would go black every 3-4 seconds. It went pretty smoothly despite that, but I do recall it being a major time consuming pain.

RedSnapper said:

"I too have have a late 2009 27 inch iMac and have experienced this 'screen blacking' (only since upgrading to Sierra iOS). It seems to happen more frequently if the computer has been in use for several hours. Sometimes it resolves by a short dab on the power button but occasionally this doesn't work and I have to power shutdown. Im sure its not a heat issue because when the power button "fix" works it restores immediately and then seems fine.
I also have an occasional issue with it waking up after being in sleep mode - sometimes it won't!

Any inside would be gratefully received but please keep the tech simple as I am a Mac-novice.

Click to expand...