Chosen Solution
I have an iMac that hangs on boot, even after having its disk erased and OS X reinstalled from Recovery Console. I just tried to boot into the fresh install, and it’s been stuck on the splash screen for about 45 minutes. Disk selection comes up in 2 or 3 minutes if I hold option- I’ve been able to boot into an external drive with a known good clone, but only intermittently- once out of every three attempts. It will open recovery console, but very slowly- takes 15 minutes or more. I can’t persuade it to run AHT from the OEM disc- the build-in CD/DVD drive won’t accept the disc, and it doesn’t seem to recognize the disc in an Apple external drive. Anything else I should try? Is this a hard drive problem, or something deeper?
I’d disconnect the hard drive and see if the machine will then accept the DVD. Next try an external USB flash drive or an external hard drive with a system on it.
I had a similar issue with my iMac, of the same model. Despite Disk Utility saying that the health of my drive was fine when booted from an external device, I went ahead and replaced it anyways. The slow loading times have since been fixed. Bad/Dying Hard Drive is likely your issue
