Why is my iMac powering off or not starting at all?
After replacing RAM and installing the latest version of OS X on my 20" iMac, I used it. After a day, it didn't boot anymore. I unplugged the power adaptor, waited a few seconds and then tried again. Sometimes the iMac does start up, but in general it does not. When it does not start up, I can hear something inside turning (I don't know what it is). After a while, the sound stops. When I unplug the adapter, it works (sometimes).
I thought it might be a software problem, because it worked sometimes, so I tried re-installing OS X. All the time, during the process of installing, the iMac powered off again. It just completely shuts down out of nothing.
Today, I connected a firewire cable and I installed a new version of OS X trough another computer. This worked. The iMac booted, OS X started but after less then five minutes, the iMac shut itself down. I would very much like to know what problem could be causing this and how can I fix it?
Looking forward to hearing from you. If you need more information, please let me know and I will respond as soon as possible.
Thanks in advance,