Spontaneous reboot when streaming video

Discussion in 'iMac' started by Invizzible, Aug 3, 2011.

  1. Invizzible, Aug 3, 2011
    Last edited: Aug 19, 2011

    Invizzible macrumors regular

    Feb 9, 2003
    My late 2007 24" iMac has started doing spontaneous reboots (sometimes it freezes instead of rebooting, and I have to do a hard reset with the power button and sometimes a very loud crackling sound comes out the speakers as soon as it freezes and the sound continues until I do a hard reset). It seems to only happen while watching streaming video of any kind.

    At this point I'm still not sure if this is software related, or hardware related. I'm wondering if my video card or power supply has a problem. My hard drive died after 3 years and when I checked I found it was running consistently at 59 C degrees, which is only one degree below the manufacturer's max temp spec. I replaced the drive and have been using SMC fan control ever since, but I wonder if damage to other components was done in that first three years of baking.

    Around the same time, my Netflix playback became very choppy and is still that way. In addition to that, I have had to reinstall Silverlight three times recently, because Netflix video refused to play and I got a message saying there was a problem with Silverlight and it needed to be reinstalled. So that makes me wonder if the rebooting/freezing issue might somehow be software related.

    Before signing off I'd like to give a brief rant on how disheartening it is to find that Apple's heat management is so bad on this model. Without SMC fan control, my power supply sometimes hits 80 C degrees. I think it must be intentional, as a way of getting people to pay to have their computers either serviced or replaced after just 3 or 4 years. The OS should run the fans fast enough so these temps are never seen in the unit. This was the top of the line model when new, and not exactly cheap. It should last far longer than this. My G4 Powermac was still going strong at the 10 year mark when I sold it, and that thing saw MUCH heavier use than this iMac.

    I'd be interested in hearing from anyone who has had similar symptoms.
  2. Invizzible thread starter macrumors regular

    Feb 9, 2003
    Ok, here's the update on this problem:

    I did a fresh install of Snow Leopard onto my external FW drive and immediately updated it so it's current. I then updated to the most recent flash player and copied over my everything in my Mail folder, along with my music and pictures (including all the respective plist files). I did fresh installs of Skype, SMC Fan Control, MenuMeters, VLC, MDRP, Handbrake and MacTheRipper. I also repaired permissions 3 times during this process. So basically, it's a pretty fresh installation. Then while watching a youtube video (flash version) my iMac spontaneously rebooted. A few minutes later, while watching another youtube video (again, flash version), it locked up and I had to do a power button hard reset. I don't know enough about computers to decipher what the console is telling me, but I've attached a screenshot of my console readout for the lockup in case anyone can clue me in.

    I guess my next step will be to use html5 youtube videos and see if the symptoms persist. If it helps any of you hard core Mac fans to get mad enough to help me figure this out, I'll tell you that so far this problem has not occurred while watching online video with Windows XP, installed inside VirtualBox.:( So, are you gonna let a 10 year old version of Windows kick a modern version of OS X's a$$??? :D Please help if you can!

    Attached Files:

  3. MacHamster68, Sep 13, 2011
    Last edited: Sep 13, 2011

    MacHamster68 macrumors 68040


    Sep 17, 2009
    just avoid watching youtube in OSX then ;)
    sorry , seious now i can only think about you do it again and dont put in your stuff just a plain installation , no updates and try again then 1 update after the other then your files one after the other and always test in between, no virtual machine no windows xp no bootcamp nothing just OSX

    i first thought Harddrive failing ,ram failing but as windows works i doubt that so the cause must be in your installation
  4. Invizzible thread starter macrumors regular

    Feb 9, 2003
    My fresh Snow Leopard installation is on an external drive, and it's giving me the exact same symptoms as my old Snow Leopard installation on the internal drive gives me. Also, my internal drive is only 1 year old because the original HD died before the computer hit the 3 year mark so I had to replace it.

    If it were a GPU problem, I would expect to have the same issues when running Windows in Virtualbox, but so far that works flawlessly.

    Oh, the RAM.... Cleaning the RAM sockets with Deoxit and re-seating the RAM (along with blowing out the inside of the iMac) was the first thing I tried. No luck.
  5. MacHamster68 macrumors 68040


    Sep 17, 2009
    sorry edited my post while you where typing as i missed that it works in windows , so the root cause must be in your installtion of OSX
  6. Invizzible thread starter macrumors regular

    Feb 9, 2003
    But... the same symptoms from two different installations of OS X, on two different drives?? And one of the installations is brand new, and was installed on a drive that was first wiped using the "Secure Erase" feature of Disk Utility.

    If it is a Snow Leopard bug, I'm hoping others on here will have seen the problem and know what to do. I'm kinda shocked (and plenty discouraged) that my brand new installation still has this issue.

    I suppose it's still possible that it is hardware related and it's just a coincidence that I have not yet gotten it to fail with Windows. But it happens so frequently with OS X that I figure if it were gonna happen with Windows it would've by now.

    Oh, one other thing.... I can run this computer really hard (compressing a dvd with Handbrake, both cores at 100% for an hour) and it behaves perfectly. I keep it as cool as possible with SMC Fan Control, but it still warms up a bit when both cores are maxed like that for so long. And yet, no problems at all. Ditto for when I'm watching video off the hard drive - no issues at all. So, those are two other reason why I suspect it's probably not hardware.
  7. MacHamster68, Sep 13, 2011
    Last edited: Sep 13, 2011

    MacHamster68 macrumors 68040


    Sep 17, 2009
    i suspect one of your plists files or some other file you transfered form your old installation is causing the problem

    like for example that problem here if you use Safari , just example but that crashed some sytems too , ok it was 2009 and the problem is likely fixed already , but you never know if you tranfer old plists , you got nothing to lose , the worst that could happen is its crashing again

    but if i get a problem like that i do a clean install without any file transfer first to get to the root make a backup transfer one file make backup transfer another make backup... crash and i know it was the last file that caused it
  8. Invizzible thread starter macrumors regular

    Feb 9, 2003
    I've found lots of articles like the one you linked, which talk about reinstalling the flash player. I did that twice and the problem still didn't go away. And I've tried two different versions of the flash player, the current up to date version and a slightly older one, and had the problem with both of them.

    I've only transferred over a few plists from my old system, for things like Skype, iChat, iTunes, iPhoto.... but I'll try putting those in the trash and see what happens.
  9. MacHamster68 macrumors 68040


    Sep 17, 2009
    i have no other idea normally i would say HDD or GPU or Ram problem if a "older" Mac is crashing
    but if windows via virtual machine is working flawless then it has to be a problem within OSX

    apart ..have you tried it with another browser ..FireFox for example
  10. Invizzible thread starter macrumors regular

    Feb 9, 2003
    Yeah, I know. It's driving me crazy. I was hoping others would have the exact same issue, but so far I'm the only one. It's as if Snow Leopard (or flash, I'm still testing html5 stuff) has a bug that only effects me.

    Anyway, thanks for your suggestions! I hope others can chime in on this as well. Right now even my 2 year old netbook running XP is more reliable than my top of the line 2007 iMac on Snow Leopard. That's just not right.:(

    Oh, and yes.... Firefox, Camino, Chrome... they all locked the machine up with streaming video.
  11. Sharangad macrumors member

    Oct 19, 2008
    It sounds like something's wrong with the GPU. OS X uses hardware acceleration on most modern Macs for H.264 video in flash.

    It works in Virtual Box because the VM uses software decoding of the video stream. The VM can't access the video decode hardware.

    You could try turning off hardware acceleration in flash player. You can load up a flash video, pause, right click on the video frame and select settings and untick hardware acceleration. I think this will resolve your problem,
  12. Invizzible thread starter macrumors regular

    Feb 9, 2003
    I think I've finally (I hope!!) found the culprit. I guessed that maybe there are addresses in RAM that Virtualbox never touches, and so I pulled out one of the two 1 GB RAM sticks and was able to run streaming videos all day yesterday without a single lock up or spontaneous reboot. Since I haven't been able to go even 1/2 a day since this problem began, I'm hoping either the RAM (or, less likely, the RAM slot) is defective.

    It still strikes me as peculiar that this only happened during streaming video, because I would think a RAM problem would happen while doing anything at all. But maybe I don't multitask enough to hit those bad RAM addresses???

    As far as the gpu, a friend suggested that also and gave me a link to a stress test for the gpu which I haven't run yet. I will try it, but since the problem never occurred while playing videos off the hard drive, I'm thinking [hoping!!] the gpu is fine.

    Thanks for the input everyone! I really hope it turns out to be something as simple and cheap as bad RAM!!
  13. TraceyS/FL macrumors 601

    Jan 11, 2007
    North Central Florida
    I had a bad ram chip in my kids emac. It was occasionally showing up until I did an OS install. Then i could have it rear it's ugly head every time. I didn't think it was ram, but I think apple did. I had added some a couple of months before. Because i could hit it with predictability I was able to narrow it done to a certain module instead of the slot. Turned out to be the "new" crucial one and they were awesome on the replacement.

    So since you have it predictable and think it is the ram, play musical modules with a chart and see if it does it.

    But the GPU on the hardware side sounds plausible too.

    Good luck!
  14. Invizzible thread starter macrumors regular

    Feb 9, 2003
    That actually brings up another point: When I did my fresh install of Snow Leopard the other day, trying to figure this all out, I never ran into any problems. Once again, a situation where I'm surprised it wouldn't hit a snag if the RAM is bad.

    As far as the gpu, I'm still thinking that since it never had a problem with video on the hard drive, the gpu is fine. Also, my machine is old enough (mid 2007 24" iMac with an ATI Radeon HD2600 gpu) that I'm not even sure it can take advantage of hardware acceleration. I seem to remember people complaining back when my iMac was new about the gpu being a weak link in an otherwise decently powered machine. But I'm not knowledgable enough about gpu models to be sure.

    But I will run the gpu stress test anyway.
  15. Invizzible thread starter macrumors regular

    Feb 9, 2003
    In case anyone ever has this problem, I thought I should finish my story. After ordering two new RAM sticks (2 GB each), I've determined that the problem is not caused by bad RAM. Of my now four RAM sticks (two original 1 GB sticks + new ones), each one works perfectly when it's the only one installed in the machine. But when both RAM slots are being used, the problem shows up (again, only when watching streaming video... weird) and it doesn't matter which combination of sticks I'm using. I suppose whatever hardware is responsible for coordinating the use of the two sticks is responsible. Since I've worked for many years as a component level bench tech, if there's anyone reading this that would happen to know what component on the pcb does that job, I'd be interesting in hearing about it. If I knew which part was bad, maybe I could replace it. Anyway, the end of my story is that I'm running with only one slot filled now, and have no problems, and am crossing my fingers in hopes that nothing else goes bad on my motherboard.

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