i have a nice iPhone 3GS which has a curious behaviour.

I'm not using it often but when i'm doing CPU intensive things like a game, it just shuts down suddenly, screen becomes black an i can't restart it without putting it on the charger. It's not hot.

Then i plug it, and it just boots and is runs ok with the same battery level as before the crash.

I thought changing the iOS would fix that but it doesn't .. i'm on iOs 6 and it's still the same behaviour

What could i do ? thanks

  • Sounds like a hardware problem. Maybe an Apple Genius at the Apple store would be able to help you out. Nov 23, 2012 at 20:48
  • Ok I'll try to do that ... I was thinking about a short circuit or something like that but other people told me to restore the phone to fix such behaviour so i did not know what to do :)
    – Fredv
    Nov 24, 2012 at 7:43
  • Well if you didn't mind wiping the phone, it wouldn't be a bad thing to do (Settings > General > Reset). It's entirely possible the folks at Apple will want you to do that. It's really easy if you back up to iCloud. My guess is it's a hardware problem, but again, restoring the OS wouldn't hurt anything. Nov 24, 2012 at 13:24
  • That's what the phone does when the battery is depleted. Games drain the battery very quickly and a 3GS is so old that it probably runs out of power when stressed like that. I've seen battery levels jump quite a bit on a 3rd gen iPod Touch between playing games and other apps.
    – Ɱark Ƭ
    Jan 16, 2013 at 19:25
  • Well no the behaviour is different : when i play and use CPU strongly, it just stops. But when i plug it on a USB to restart it, the battery is not empty : it's just like it was before it stopped. I have found that it made this behaviour only with CPU intensive things
    – Fredv
    Jan 17, 2013 at 13:40

2 Answers 2


Sometimes when you run some games that is not compatible with your iPhone, it will use more power than it can to the CPU and GPU and then it will crash. Try to verify if the game is compatible with iPhone 3GS

  • A (badly designed) app could indeed crash but the phone itself should stay on anyway. As far as I know apps can't even intentionally shut down the device, so if they manage to do it it's definitely a hardware issue.
    – user56648
    Jan 10, 2015 at 14:05

If it's CPU related then it's likely heat or a problem with the logic board / processor unit.

If it's related to a certain point in the battery discharge cycle, it's likely the battery and more inexpensive to repair.

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