iMac turns off with a popping sound.

Discussion in 'iMac' started by The General, Feb 18, 2011.

  1. The General macrumors 601

    Jul 7, 2006
    A few times a day, my iMac just straight up turns off instantly. It didn't used to, but now it makes a popping sound when it turns off which worries me. It also seems to turn itself off more frequently.

    Apple hardware diagnostic checks out, so I don't think it's the RAM. I've never experienced something like this before, but I think it's a bad power supply, right?

    I have the setting "Start up automatically after a power failure" option turned on, and the computer does not turn back on after it turns itself off, it stays off. Is this normal for a bad power supply? If I unplug it and plug it back in to simulate a power failure, it turns off and turns back on by itself.

    The inconvenient part of all this is that I opened the iMac and installed my own solid state drive and upgraded the hard drive to a 3TB and upgraded the RAM to 16GB, so I think I have sufficiently voided my warranty. I supposed I can reverse the HDD and SSD mod and take it to the Apple store, but I don't have the original RAM modules so I'd have to leave those in.

    How can I test or make sure what the problem is before taking it to the Apple store? The console and system log have no valuable information in them.
  2. kevrayner macrumors newbie

    Feb 19, 2011
  3. biggd macrumors 6502


    Apr 6, 2008
    Your issue is a bad powersupply

    That's the pop noise. And that's why ur Mac shuts down
  4. The General thread starter macrumors 601

    Jul 7, 2006
    Nope, but I got this iMac just over a month ago.
  5. Voondebah macrumors member

    Mar 28, 2010
    My only suggestion would be to install iStat Menus. it has a 15 day trial period, and it will allow you to see the values of voltage sensors. Perhaps if you're power supply is having problems, there will be some instability with these values.

    I suppose I do have another suggestion - you could try and tax your system to see if heavy power draw is tripping a faulty power supply. Turn up the brightness, get the CPU and HDD working, and see if that causes issues.
  6. Ace134blue macrumors 6502a


    Sep 17, 2009
    Upgrading your ram does not void your warranty, and i doubt HDD upgrade does either. If they ask, just say you got Mac authority to upgrade it for. (they are certified to do that work).

    As for your problem, its a PSU issue. Many iMacs had issues have had problems with power supply. I had 2 iMacs, 1 21.5 and 27in with this horrible ringing noise which was made worse by making screen brighter, They both did this because of the PSU.
  7. The General thread starter macrumors 601

    Jul 7, 2006
    I took it to the Apple store and apparently the SATA controller has primitive support for 3TB drives but they don't support it because it's unstable. He said that's one of the reasons why 3TB drives are not available for iMacs at the moment.

    The 3TB drive is crashing the SATA controller, which makes the computer turn off. The solution is to take the 3TB drive out and put a <2.2TB in.

    I wish my external enclosure supported 3TB drives. This also means I'm going to have to buy a 2TB western digital drive, because all of the spare drives I have are Seagates and the thermal sensor cable won't work on them.

    He told me that normally my having configured it the way I did would void the warranty, but he wasn't too worried about it and wouldn't put it in his notes. :)

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