# iMac A1225 constant restart



## bulo30 (Jul 17, 2013)

Hi,

I have a faulty iMac 2008 A1225 24", core2duo 2.8, 4GB DDR2-800 from a friend.

I tried many things to repair (replace RAM, HDD, startup without screen connected, check caps on PSU visually, PRAM reset, smc reset)... nothing works.

The issue is:
--- when starting up the machine runs for 8 minutes and the restarts every 5 to 10 seconds.

There is no OS installed. When trying to install OS X mountain lion, I can format the HDD, start installation but after 8 minutes the mac restarts continuously. Everytime the same happens at the same time interval.

The LED's light up correctly on mainboard.

Any ideas? I have a multimeter, but don't know what to measure.


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## MartyF81 (Jan 23, 2013)

Sounds like it is overheating. Macs will shut themselves down when they heat to prevent damage. It is probably taking 7 or 8 mins to heat up and then shutting off. Then the next time it boots up since everything is already hot it only takes a few seconds for it to reach temp and shut off again.

I would install something like iStat Menu to watch the temps and see where it is getting to in that first 8 mins.

Another thing it could be is the battery is bad. So during that first 8 mins, try installing a battery health app to see how that battery is doing. If the battery is bad, it could cause this issue when the initial charge disperses after 8 mins.... so it shuts off. When you turn it back on the battery may only have enough charge to boot up and shut down again.


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## bulo30 (Jul 17, 2013)

Thanks for your answer.

The issue is not on a laptop but on a iMac, so there is no battery.
It does sound like an overheating problem, however when i startup the iMac with lcd taken off i can feel no extreme heat comming off the parts.

You also mentioned a few apps to install, but I have no OS installed since the iMac allways restarts during installation so that's no option.

I do have coolerpaste, but i want to replace the paste only if I can rule out the hardware because this model seems to have a lot of problems with bad caps.


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## MartyF81 (Jan 23, 2013)

Sorry I saw iMac and for some reason my brain though Macbook!

Even with the LCD off, the core temperature of something like CPU or other area may not even be noticeable externally. Think of it this way, on for example a laptop there is barely a thin piece of metal between the users legs and that hot CPU... yet you can hardly feel any heat at all. There could be something else blown up too..... but really sounds like hardware issue to me.


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## bulo30 (Jul 17, 2013)

The overheating was my first thought as well. 
But since I read there where so many problems with 2007->2009 iMac PSU and logicboard I didn't want to do all this work for nothing.

So maybe I should disassemble all the way and replace all coolerpaste. Or maybe only the CPU because that seems to be the culprit.


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## bulo30 (Jul 17, 2013)

Ok, I applied fresh coolerpaste on CPU but still same problem.


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## sinclair_tm (Mar 11, 2005)

I'd apply new paste to all items that used it. Also make sure you completely clean everything that had paste to make sure you get proper heat transfer. Also make sure you are using the correct amount. Too much will also let things over heat. But if that doesn't fix it, I wouldn't bother spending any more time on it, as it's not worth it. It'll be cheaper to get a new Mac Mini then to fix that iMac, and the Mini will be a better machine.


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