27" iMac Freezes, LOUD screeches from speakers?

Discussion in 'iMac' started by gmanist1000, Jul 5, 2011.

  1. gmanist1000 macrumors 68030


    Sep 22, 2009
    Well the problems seem to continue with my new i7 27" iMac.

    Today, my computer froze on me and as soon as it happened, the iMac had a very LOUD screeching sound coming from the speakers. Computer totally unresponsive, I had to push and hold the power button to turn it off. This definitely freaked me out because it was just all sudden and it was so very loud.

    I posted a while ago about my computer just freezing and I would have to restart it holding the power button. It never had the loud screeching from the speakers when it did freeze a while ago, but now every time it freezes the screeching is there.

    Any suggestions as to what my problems may be? I have added an additional RAM into the computer and I'll list the specs if it helps at all. I also have a 24" cinema display plugged into the computer.

    27" - 3.4GHz i7 iMac
    1TB HDD
    AMD Radeon 6970M - 2GB VRAM
    12GB RAM (came with 4GB, I upgraded to 12GB)
  2. Besk one macrumors member

    Oct 27, 2009
    Take directly to AppleStore or a friendly Apple Authorized Service Provider, you have a hardware issue that's probably not RAM related.
  3. durruti macrumors regular


    Mar 26, 2004
    First, can you roughly, recreate the problem?

    Then, if you still have the original RAM leftover, do a guess and check.

    Put in original RAM. Do things to create the problem that happened with the upgraded RAM. If you can't recreate the problem, then the issue most likely is the RAM.

    If all else fails, you can always try a PRAM reset and/or SMC reset.
  4. gmanist1000 thread starter macrumors 68030


    Sep 22, 2009
    I did a PRAM reset last night, and the problem happened today so that didn't fix anything. Also, I will try the guess and check and see if that does anything.
  5. FrankHahn macrumors 6502a

    May 17, 2011
    Improperly installed RAM sticks could agitate the machine and make it screech. I had such problems with a PC some time ago. Check to see if all the RAM sticks are well secured in their slots. If any RAM sticks are physically defective, this kind of problems may also arise.

    As suggested in a previous post, leave the preinstalled memory in the machine and see if your problems go away.
  6. gmanist1000 thread starter macrumors 68030


    Sep 22, 2009
    Testing out the preinstalled memory by itself as we speak. Will repost with my findings.
  7. dazakun, Sep 11, 2012
    Last edited: Sep 11, 2012

    dazakun macrumors newbie

    Sep 11, 2012
    I've experienced similar symptoms to the original poster's description. I have an iMac 27" 2010 model. This may be related to the following:

    I've looked on numerous forums regarding the freezing problem I was having. This problem would arise on a wide range of systems.

    Symptoms included but were not all always present - usually when I am loading the system with games/heavy load processes:

    - Full system freeze, screen still on.

    - Loud cracking noise coming from speakers (relative to what volume was at when the freeze happened). This is probably a result of the system hanging, not an alien invasion.

    - Computer asleep but I cannot wake up unless hard reset with power button.

    - My screen backlight was also damaged (permanently dimmed) near the left side, and progressively got worse over time. This was fixed (replaced LCD 27" display $600+ and covered by my creditcard extended warranty)

    Basically, what I've come to realize which has not been well documented as far as I could find relating to this problem - is that the system is overheating and causing these freezing errors (and LCD damage in my case). Prologned occurances could result in different system part failures.

    How do you fix the overheating problem? Give this a try, it's worked so far for me and I've actually been able to continue video/photo editing without having this annoying freeze.

    Search for and download 'iStat Pro' (widget addon that lets you monitor your system temperatures... compare it before and after the fix)

    Search for and download 'SMCFanControl (a great little app that allows you to change your system fan speeds) - I did not know this was possible, and have never heard the fans go this high when it was being run automatically by the system. The fan's are obviously louder when set to max, but is well worth the system cooling results.
  8. gmanist1000 thread starter macrumors 68030


    Sep 22, 2009
    I posed to this thread 3 years ago, and my iMac just did this to me again tonight. Scared the living crap out of me! The volume was all the way down on my computer, but the screeching was extremely loud.

    The only changes I've had to the machine is that it's had the backlights replaced.

    The computer hasn't done this in 3 years...

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