Why, after falling, is this iMac cycling on and off?
I am considering buying a defective iMac, and this is what the seller can tell me about it:
"The computer will boot for a minute and then shut down and restart itself and continue this process and the restarts get faster till it wont do anything. It may only run for 3 min on first power up before the restarts happen.
This began happening after it took a fall from a desk and after replacing the (shattered) glass pane on the front."
Any guesses on what would be wrong with the thing? My first guess would be the logic board, but then again, I would also question the power supply. I just don't wanna buy the thing and be stuck with a bricked computer, as the parts are pricey. And yes, I know what I'm getting myself into... I've bought and sold defective computers quite a bit.
I agree with Sterling, this sounds like your heatsink could have come loose. I'm not sure if this is what you mean Forrest, but what we suspect is happening is that the heatsink is no longer making a good contact with your processor. The job of the heatsink is to remove as much heat as possible from the processor to prevent it from overheating.
Because the heatsink is likely no longer attached properly to the processor, the first time you boot your computer up, it takes a few minutes for it to get too hot, at which point it will auto-shut off the whole computer to stop itself from melting. The next time you start up the computer, the processor is already a bit warm, so it takes it less time to get to a critical temperature where it will shut itself down. Every time you turn on the computer, it will start off a bit warmer than the previous time.
I've had this problem on a PC of mine in the past, however the problem there was dust on the inside clogging the fan and preventing it from working properly.
I suggest you follow this guide to open your computer and re-seat the heatsink / cpu fan, applying arctic silver if necessary. Make sure you dust out the computer while you're in there, and you should be good to go. :)