Update: iMac Nvidia Graphics Card Failure

Discussion in 'iMac' started by schouser, Feb 22, 2011.

  1. schouser macrumors newbie

    Feb 8, 2011
    For those who may have been following the threads relating to the iMac screen artifacts/glitches/flickering, I wanted to give an update on my situation.

    I have a early 2008 iMac (iMac8,1) with the optional Nvidia 8800GS upgraded card. About a month after upgrading to Snow Leopard my screen began flickering (the top 1/3 of the screen would be rendered, but the bottom 2/3 would flicker black and eventually become solid black; the mouse was still tracking, but couldn't click anything or force quit). Upon restart artifacts showed up on the Apple logo screen and the system wouldn't ever get past this screen. Reset PRAM & SMC, no improvement. Took iMac into an Apple Authorized Service Provider for repairs (under warranty). The first flickering happened while I was playing World of Warcraft.

    Current Report:
    The Apple Authorized Service Provider replaced the Nvidia 8800GS and the logic board. I've had the repaired computer for 72 hours and the issue seems resolved. However, from the reading I've done, replacements I read about in this scenario have lasted from 15 minutes - a month. I'll update again if the replacements fail.

    Being the curious person I am, I'm trying to come up with theories to explain the issue. I have a question for others out there that have ever had the problem of: an initial video card working for over a year before breaking, followed by multiple replacement graphics cards breaking within a month:
    1) Were you using an Uninterruptible Power Supply (UPS) or surge protector?
    2) During your repairs, did Apple ever replace the Power Supply? If so, did it help?

    Related Threads:
    Early 2008 24" iMac With Possible Graphics Issue?
    iMac 24" / GeForce 8800 GS: Vid card dies every month, needs replacement
    Intel iMac (Early 2008) Has vertical lines on the screen and doesn't boot.
    iMac freezing during boot
    NVIDIA 8800GS Failure Rate
  2. flipster macrumors 6502a

    Mar 14, 2010
    LOL, go look at my thread, someone else just added to it.

    I personally have this model computer, 1 year and 3 months now, and have had no problems yet.

    I game everyday and the GPU diode never goes over 170F which is good. I play Counter Strike: Source, and Left 4 Dead 2 everyday. Gaming probably about 3 hours a day.

    I need to know: What do you do on the imac daily?

    Install a tool called istat menus pro, and tell me the gpu diode temperature when it happens

    When did it start happening?

    I find it strange that my imac is put under insane workloads everyday and doesn't have any problems
  3. schouser thread starter macrumors newbie

    Feb 8, 2011
    Flipster, are you using Snow Leopard?

    I had no problems before 2/8/11 (I upgraded to Snow Leopard about a month prior). I game about 30 hours a week (World of Warcraft/Starcraft II). Both use OpenGL (as does Left 4 Dead 2). The crash happened while playing WoW. I figured it was a software kernal panic & I had to force a shutdown. After rebooting, I restarted WoW and it froze within minutes, same flickering. I forced a 2nd shutdown. This time, after rebooting, I figured corrupted game files, so I tried a different game (SC2), flickering & freeze within minutes. I forced a 3rd shutdown and this time the computer booted up with 3-4 vertical grey bars about 1cm in thickness across the Apple Logo bootup screen; the screen was frozen and never changed from the bootup screen. Time from seemingly flawless to unable to boot was about 45 minutes. No warnings or artifacts prior to the initial freeze.

    Several people have suggested "bad video cards" right off the bat; but that doesn't explain why replaced video cards fail within days/weeks. I suspect the failing video card is secondary to another issue. One of my initial theories was a glitch between Nvidia cards & the Snow Leopard 10.6.3+ updates. A lot of reports came in with crashing video cards/artifacts after the 10.6.3 update was released. This update made some changes to OpenGL. I'm also entertaining the idea of an incompatibility between software/hardware dealing with 32/62-bit processing. However, if it was as simple as a "glitch between 10.6.3 OpenGL/CL and Nvidia CUDA cards, like the 8800" then I'd expect a much larger population reporting problems, even if the Nvidia card was only available in a handfull of 2008 iMacs. So there may still be another variable playing into the mix. My best guess would be power supply. Perhaps users without a surge protector (or poor surge protection) are experiencing voltage inconsistencies that trigger the glitch.

    So... do you have Snow Leopard? Do you use a surge protector? I'm totally shooting in the dark... but it's really fun to theorycraft. =)
  4. goMac macrumors 603

    Apr 15, 2004
    Nope, it's the video card. The entire 8X00 line is known to be defective. Same deal in the Mac Pros and Macbook Pros.

    The reason the second one dies quicker is because likely it's a used part.
  5. flipster macrumors 6502a

    Mar 14, 2010
    No, i just plug the thing into the wall lol. I game about 40 hours a week, so the gpu diode is always at 170F and it works fine.

    Install something called istat menus pro. You really need to watch the gpu diode temperature and report back what temperature it's doing this at.

    As for your theories, you may be correct. Someone actually had the PSU replaced and apple did some crazy thing with the voltage and it actually underpowered the graphics card, and although i think it worked (i cant really remember), it decreased the graphics card performance and that person complained because they had specifically paid for a machine that would be more powerful, not less powerful.

    Apple probably knows that the whole 8 series line is defective, and just gives 27" replacements (great customer service imo). I don't even think they have many 8 series gpus left for replacements, so a replacement iMac is usually in the question. It does suck in a way because if this happens out of warranty, you are out of luck. The 8800 GS is still one of the most powerful GPU's used in the iMac's.

    Like I said though, i have no problems whatsoever. How old is your imac? Like when did you purchase it to now?
  6. schouser thread starter macrumors newbie

    Feb 8, 2011
    It had not occurred to me that Apple & its Authorized Service Providers would be using used parts to repair... that makes sense. Still seems odd that everyone who gets a replacement is getting a used card that only has weeks left, but it's a good theory.

    Flipster, I may have missed it, but did you answer whether you're using Snow Leopard 10.6.3 or higher?

    I'll install a temp sensor and report back. As for the age of my iMac, it's a 2008 model. I purchased it new in August 2008, so it's 2 years & 6 months. I also read several reports about undervolting. One guy was knowledgeable enough to actually test the card after taking apart the iMac to find the voltage, and that it was indeed undervolting the card. A separate case I read about involved someone who's servicer replaced the PSU & graphics card. It's the only case I've read thus far where an 8800 Nvidia chip in an iMac was replaced and didn't fail again. It's possible that it did fail and the guy never reported back, though. But at the time of writing I think the 2nd Nvidia card had been going strong for 6 months.
  7. flipster macrumors 6502a

    Mar 14, 2010
    Sorry, ive been using snow leopard 10.6.6 with no problems. Although when snow leopard came out, i zerod out my data completely, deleting everything on the hard drive including the operating system so i could do a clean install. i did that about 7 months ago, and after that it ran a lot smoother.

    As i said before, the cards usually fail within 3 years. Take it to an apple store, a lot of stories ive heard them actually replacing the machine for free even for people without applecare. you could write an email to apple to expressing your feelings and how the 8 series is defective.
  8. BlackMax macrumors 6502a


    Jan 14, 2007
    North Carolina

    1. Yes, a UPS
    2. No, Apple never changed my Power Supply during my repairs.

    I was still running Leopard (OS X 10.5.8) on my 24" iMac.
  9. Ed85 macrumors newbie

    Nov 30, 2011
    London, United Kingdom
    I know this thread has been inactive for a few months, but I thought I'd add my info on the situation, since I'm also a victim of the 8800 issue in the early 2008 iMac.

    At the end of September, the 8800 packed up. I wasn't even using the computer for anything - just listening to songs on iTunes as I got ready to go out. When I idly pressed the next track button on the keyboard and nothing happened, I looked at the screen and there were colourful speckles all over the screen. Clearly a GPU issue. The computer was frozen. I took it into a store and had the GPU replaced (after having a bit of an uphill struggle with the Genius, who wasn't convinced the obvious GPU issue was a GPU issue).

    After about a month of having this thing replaced, the screen started flickering and then there would be a freeze. At the time, I was in Windows XP in boot camp, playing Skyrim. No graphical artefacts this time, but flickering then a freeze. Took it in, and it's still in there, being 'repaired', although we all know this isn't the end of it. I'm considering just selling it (being honest about its repair history) and getting a new one.

    This thing about Apple replacing the Mac outright sounds good, but I'm not convinced they would do that here.

    One thing mentioned during both hardware tests the Geniuses (Genii??) did was the lack of a GPU Proximity Sensor, which I'm guessing is the temperature sensor near the GPU.

    Very frustrating, and costly getting a taxi to take my heavy iMac to the Apple store!!

    Anyone else got any other experiences, info on that Nvidia lawsuit or how to escalate the situation to just get a replacement and to pay the difference for an upgrade?
  10. Evcowebgal macrumors newbie

    Jul 19, 2012
    Conifer, CO
    New Victum

    My warranty expired in November of 2011. In Feb of 2012 my screen kept going black. The computer was still working but I could not see anything but black (not gray, black). I took it to the Apple Genius Bar. They replaced a cable and said the fan may need to be replaced; and if this did not solve the issue it was likely the logic board. He told me that part was expensive and if it needed to be replaced I should probably buy a new iMac...

    It seemed to work again until last week. The screen started to act oddly just out of the blue. It would get pixely and lock up. After another day of restarts it eventually would not boot and the screen had vertical lines which eventually progressed to vertical lines with horizontal lines between them. I read through the forums and reset the PRAM, which resulted in nice clean vertical lines on a gray background. Will not boot and "D" on the restart does not work, nor does inserting the OS disk to check for hardware issues.

    I ordered a new 21.5 iMac which came yesterday, but I don't want to give up on my 2008 iMac if it can be fixed. I told the Apple Genius in February that it was the 8800GS board that was causing the initial "black screen" issue, but he said that was only a Macbook issue... so, I have a perfectly good computer that I've upgraded to Lion, added memory to, and used almost exclusively since 2008. I now have a brand new shiny 2011 (which I just purchased and have to wonder why I get that model in July of 2012) with a bigger hard drive, a faster processor, a bunch of memory and a substantially smaller screen (finances you know...)

    If this issue can be resolved I'd like to get my old fellow back up. I've worked on the white iMacs and they seem to last forever! It does not seem right.

Share This Page