Display problems with white iMac Core 2 Duo

Discussion in 'iMac' started by baummer, Feb 17, 2009.

  1. baummer macrumors 6502a

    Jan 18, 2005
    Southern California
    I am currently having a bizarre batch of problems relating to my iMac's display.

    I have a white 2.16ghz Intel Core 2 Duo iMac with 3 GB of ram. I have made 2 hardware modifications: 1 500GB hard drive self-installed (to replace the stock 250GB HD) and the installation of 1x2GB & 1x1GB 667mhz DDR2 memory.

    I installed a trial of Adobe Photoshop CS4 a couple of weeks ago. The problems began after that with the system's display completely locking up (though the machine was still operating i.e. the volume function on the keyboard still worked). I figured it had to do with Photoshop's new usage of the graphics card, so I disabled that to see if it would help, it did not. Other symptoms:

    • Random lines (like TV scan lines) across the screen in specific applications in no particular order that sometimes disappear on their own or after the app has been closed and restarted (as seen here: [​IMG])
    • Random splashes of magenta and yellow coloring over certain graphical elements that disappear just as randomly as they appeared (either by a click of the mouse or typing on the keyboard)
    • Random manipulation of textual information on the display
    • Progress bar for copying, etc. actions displayed off-center
    • Complete screen blackout that requires machine restart to function again
    • Mouse freezing that requires unplugging and plugging in again for mouse to return to normal operation

    All of these problems began after the installation of CS4 and were not present before. I have removed CS4 and the problems still occur randomly, although things seem to be getting worse. I've checked the Console for any sign of problems but the logs have not produced anything worthwhile, which makes me believe this is a hardware problem.

    I purchased the system in November of 2006 from my university's campus store and as they have their own repair center did not purchase Apple Care and also assume my warranty is expired. As I am an alumnus of that university and not currently attending I no longer have access to the campus store/repair center.

    So, that said, what are my options given this information? Obviously there is some sort of problem with the graphics card, is this something that can be replaced or does it require a full logic board replacement? Can this be taken into an Apple store for repair, even though I've taken the machine apart to install a new hard drive? Thanks for your advice in advance!
  2. superbungalow macrumors member

    Dec 29, 2008
    If you're near one, at least try taking it to an Apple store. I hear they're very friendly about these kind of things.
  3. AlexisV macrumors 68000


    Mar 12, 2007
    Manchester, UK
    The GPU is soldered to the motherboard I believe. It is uneconomical to replace it.

    I'd backup and try a full reinstall of OS X.
  4. baummer thread starter macrumors 6502a

    Jan 18, 2005
    Southern California
    What would a full reinstall of OS X do if it's the GPU? Last I checked OS reinstalls rarely fixed problems with hardware.
  5. johnsy macrumors 6502

    Nov 15, 2006
    Yah it might be toasted. You might try to change back memory, or reinstall OS, as a last result and just in case, but if it is gpu (looks like it), then it is toasted. Price of a replacing a gpu (full board) is too much vs new imac.
  6. rocote macrumors newbie

    Feb 19, 2009
    iMac Graphic problem!!!

    Hey baummer, I have the same problem with my iMac. Weird graphic line and parts of some graphic screen dissapear. I have done a complete OS X installation and didn't wokr out. I really don't know what to do with this. Note: I also install Adobe CS4 a few weeks ago but don't know if it is the problem.
    If anyone has a solution, pls email me.
  7. Deathgod macrumors newbie

    Feb 19, 2009
    i have the same prob on my new imac

    faint red/pink lines that hang in the gray toolbars

    anyone have a fix ?:confused:
  8. Drumerdude macrumors member

    Feb 15, 2009
    Photoshop probably requires a better graphics cards/chip. Yours mite of been to old, or not good enough. It possibly might be dying on you. That is just what I think though. You can try bringing it to the apple store, But they MIGHT have you buy different parts. I think you are better of getting a new computer.
  9. molex macrumors newbie

    Sep 24, 2007
    Check this out >>>>


    This problem seems to be not uncommon. My late 2006 Intel core 2 Duo white imac has the EXACT same problems. Apparently, apple didn't provide enough cooling power for the Nvidia 7300/7600 graphics cards in these iMacs, and after a while they start to act very odd, exhibiting the problems you noted plus (in my case as well as many others) random freezing several times a day, usually related to streaming or playing any video content.

    The only "fix" is to replace the graphics card, which CAN be done but it's a pretty tough job apparently, taking several hours and requiring that you completely dismantle your iMac and remove the motherboard since the card is on the back of it.

    Contrary to a previous poster's assertion, the graphics card in these iMacs is replaceable, it's not soldered to the board. You have to order a SPECIFIC card though, not any old Nvidia 7300/7600 card will work. Apparently one of the few places that stocks these cards is here:


    You'll find step-by-step instructions for replacing your video card in the first link in this post. It's NOT easy, and NOT for the weak of heart. Basically, if you don't have a lot of skill/experience with these kinds of things you should approach this fix only if you're willing to buy a new iMac anyways if you toast this one.

    If you have the dosh you could probably have Apple do this, but personally I'd rather risk ruining the computer than pay Apple a thin dime to fix a problem that THEY created, tha bastahds.

    By the way, if you (or anyone else) does this, be sure to download a fan control utility (a few different ones are available, google it) and increase the speeds of all your cooling fans, otherwise the new graphics card you just spent hours installing will also eventually over heat and fritz out. I'm planning on drilling several new vent holes in the back of my iMac to assist with ventilation duties, since there's obviously not enough.
  10. indg macrumors 6502

    Feb 7, 2007
    this is a common problem with the late 2006 intel imacs (Model ID: iMac5,1). it's caused by a faulty logic board. apple refuses to acknowledge this as a widespread problem.


    if you have a 20" or 17", the ATI X1600 gpu is soldered onto the logic board, so it can't be easily replaced.

    if you have a 24", you may be able to replace the nvidia graphics card. however, since the problem is actually with the logic board, many people who did replace the gpu end up experiencing the same problems again a few months down the line. why a few months later? because when they opened up their imac, they cleaned out some of the dust inside the casing. then a few months later, dust buildup starts blocking the ventilation and voila, same problems.

    the problem is not that the logic board is overheating, but that there's a defect in it that causes it to start glitching and freezing/shutting down the system when the temp starts approaching 120F (49C), which isn't hot at all.

    if you contact apple about this, they'll tell you that you need to buy a new logic board ($600-$800) if you don't have applecare. this is not acceptable. do not, i repeat DO NOT, pay them to fix this. point them to the apple discussions thread if you have to, but let them know you're not the only one having this problem. the more people speak up and refuse to pay to fix THEIR problem, the more they'll realize they have a real problem on their hands. unfortunately, it may take a class action lawsuit for apple to actually issue a product recall, like they did with the g5 imac and g3 ibook logic board recalls.

    in the meantime, i suggest your run imac fan control and bump up the lowest fan speed setting for the CPU (e.g. 1600rpm), and lower the upper threshold (e.g. 170F) so that the fans speed up faster than the default scale as the internal temp gets hotter.
  11. M87 macrumors 65816

    Jul 18, 2009
    I've had those lines on my 2006 iMac. They went away at some point, but now I have a much worse issue—my whole screen goes black!
  12. indg macrumors 6502

    Feb 7, 2007
  13. ntoxicated macrumors newbie

    Aug 29, 2009
    Phoenix, AZ
    Replace the Logic board

    I took my iMac 20" C2D to Apple, and the Genius Bar tech knew exactly what needed to be done. They replaced the motherboard and its working properly now.
  14. jamdr macrumors 6502a


    Jul 20, 2003
    Bay Area
    I have a 24" white iMac and have the same problem. Various parts of the screen get corrupted with those multi-colored static lines or sometimes just green pixels. The funny thing is I never had this problem until just yesterday during this heat wave when the computer got really hot. I guess it was enough to fry everything. Now I wish I never turned my computer on that day :rolleyes:

    This is too bad. I spent a lot of money on this computer and planned to keep it for at least 5 or 6 years. Now I learn there is some defect in it from the beginning that made it impossible for it to last that long. I don't know what to do at this point. Am I just suppose to buy a new computer, even though this one's just a couple years old?
  15. J&JPolangin macrumors 68030

    Jul 5, 2008
    Thule GL @ the TOW
    ...do you have applecare?

    The repair is covered if you do...
  16. byke macrumors 6502a


    Mar 29, 2007
    LDN. UK
    I have been having issues like this for over 1.5 years .... I use smc fan control on full wack, but that wont last too much longer as its getting worse by the day ......

    Not a happy boy.
  17. I3eXa macrumors 6502

    Aug 24, 2004
    I bought a 20" a while back and its still under applecare but maybe my situation is different cause I get green blocks upon editing images every once in a while. Here's a screen shot. What do you think?
  18. defektion macrumors regular

    Jan 29, 2010
    I hate to revive an old Post.

    But I got an 20" iMac C2D 2.16ghz for free (No Applecare Left), and I WAS experiencing the same problems you were.

    - Random Horizontal Lines
    - Random Lock ups

    When I first booted it up in Snow Leopard, there were horizontal lines and lock ups.

    I ran iStat so I can monitor the GPU temp. While it was idling it would be between 40C - 50C. Which I found quite hotter than normal during idling.

    So I took it apart all apart, and dusted the computer. After dusting it I turned the computer on. Great! everything seems to be working. GPU temps didn't really get affected at all. I ran Quake 4 in bootcamp and it ran quite well. Then I ran Front Row... Random artifacts, and lock ups.

    I guess I Could have ran SMC Fan Control to bring the temps down. But who knows how long it'll help.

    I took the iMac apart again, took out the logic board. Removed the Heat sink from the logic board both CPU & GPU thermal compound was old. nasty. dry. So my conclusion was that it wasn't transferring heat very well.

    So cleaning off the GPU & CPU from the old nasty pasty stuff. I replaced it with Arctic Silver 5, using only the required amount to cover the surface of the GPU & CPU (that square shiny area) not the whole CHIP. And Dusting the fans 1 more time REALLY well. put it all back together.

    Suprise suprise, the temps have dropped significantly. Instead of idling around 40 - 50. It dropped to 28 - 35. Peaks at around 52.

    I ran Left 4 Dead under Windows 7 using the recommended settings. It's playable, played it for 10-15 mins. No Lock Ups. Graphic errors or anything. Booted back into Snow Leopard, Watched a DVD, ran iTunes, surfed the net. no problems yet. but the GPU was getting a bit warmer. Then I ran front row. Played some Quake Live. No lock ups or Freezing.

    So to concluded my experience, Get your hands on an apple service manual (or go to iFixit) find out how to take out your logic board. Replace the thermal paste (Use Arctic Silver 5). Dust DUST DUST!

    I would only recommend replacing the thermal compound if your
    i) To Cheap to pay Apple for a new logic board
    ii) Your iMac is out of applecare and the problems are frequent.
    iii) Or if your received the iMac for free, and you have nothing else better to do than fix it.

    This is a Temporary Solution only, and Not sure how long it will last. But this will help for the time being if you can't justify buying a new iMac right away.

    To me i see it was getting and iMac for free if I can fix it. :D
  19. Plasmatico macrumors newbie

    Mar 23, 2010
    I've been having the very same display problems reported here, for the past 12 months. I even took pictures to show to the Apple Store Guru @ The Falls mall in Miami, but he had no idea. I always suspected the video card, now this is more serious and apparently a design flaw. All else is running great except for the crappy video, other than the petition (which is a long way to reach it's goal, so maybe this is not as wide spread or people don't know about it), is there anything we could do the bring to Apple's attention?
  20. trebormesos macrumors member

    Aug 15, 2008
    I'm am right behind you
    In the same boat with my iMac

    just wanted to add my name to the list. ya never know maybe one day apple will make this right.
  21. byke macrumors 6502a


    Mar 29, 2007
    LDN. UK
    I am bumping this thread in the hopes that the latest Nvidia lawsuit to which it has agreed to fix this issue is related to this GPU.

  22. baummer thread starter macrumors 6502a

    Jan 18, 2005
    Southern California
    Sorry, but it's not. Listed clearly are the models: http://www.nvidiasettlement.com/affectedmodels.html

    The only Apple products are laptops, and since this thread is about iMacs, it does not qualify.
  23. Garrod Suspended


    Nov 13, 2008
    For many months I had been arguing with Apple over what I believed to be an inherent fault in my line of iMac. After much perseverance though they actually replaced my 2006 iMac with a brand new 27" one late last year. I've just finished documenting every step I took here:

    Link to my article.
  24. RMS1 macrumors newbie

    Apr 24, 2009
    Is there a step by step on how to remove and reapply thermal paste on the CPU and GPU? I already removed the Logic Board, I just need to know how to take off the heatsinks and clean and reapply the paste. There seems to be thermal pads on there right now.


  25. mlarken macrumors newbie

    Jun 11, 2008
    I've barely used my computer -Display problem as well as hard drive failure

    I don't know what I shoul do. Any suggestions?

Share This Page