Original post by: Michael Pender ,
It could be one of several things: - bad RAM - bad motherboard - bad hard drive The easiest way to troubleshoot the problem is to start by simplifying the things you need to evaluate. If you have two RAM modules, remove one of the two and reseat the other to make sure it is properly seated. Disconnect the power feed to the hard drive. Normally a software problem on the hard drive won't cause this issue, but a 'stuck' hard drive may draw so much power on startup that it looks like a short circuit and the safety circuitry may abort the startup sequence. Then try starting the machine again. If the machine gives you the startup chime with one RAM module and the hard drive disconnected, then you have one or both of a) a bad hard drive--most likely, they do wear out), or b) a bad RAM module--less likely since there are no moving parts, but it can happen. If the hard drive is bad, then I suggest carefully removing it and cloning it to a SSD of the same size or slightly larger. SSDs are faster than the old physical drives, use less power, generate less heat, and are generally more reliable if you pick a manufacturer with good support for Apple. I purchased a Samsung for my Mac a while ago and have been very happy with the change. Please be aware that if the hard drive is catching on startup, then it may only work a few more times. Be prepared to copy the contents the next time you get the drive spinning since it may not happen twice.