27 Inch iMac, new memory upgrade and won't start now
Hi. I have a 27 Inch (2009) iMac. Was working perfectly. Thought I'd give it a treat and upgrade to 16 GB memory (Kingston). Restarted after the easy install and performance was sloooooow. Took forever to startup and just got worse. I restarted, thinking it might help. Nope. Ran Disk Utility and it said HD needed repair. Then it couldn't repair. So I started from an external disk and Disk Genius couldn't repair. Before I reformatted the disk, I tried to reset PRAM. After that, nada. The iMac restarts on a grey screen with the spinning wheel. The progress bar moves about a quarter inch and thent the computer shuts down. I can't even start from the external disk anymore. Grrrrr. Help?
iMac (27-inch Late 2009), OS X Mountain Lion (10.8.3)