Original post by: didier godefroy ,
Hi, I have a similar issue, with my imac 27" EMC 2546 from late 2012. The fusion drive was using the 3TB seagate baracuda that was under the apple recall, and it failed. However when it was failing and I was trying to boot from various other means, as from a usb stick, external drive or dvd, and it was only booting barely about 1/3rd of the way and stalling. Now with the whole fusion drive out (HDD&SDD) and a new blank seagate non apple drive in place (a 4TB), I get the same thing, and using a large number of methods to boot: - external HD (yosemite) - external HD in recovery mode (yosemite) - external HD in safe mode (yosemite) - external DVD installer disk (10.6 and 10.8) - off the net (netboot) - USB stick (10.6, 10.8 and 10.10) - USB stick in safe mode I can get it to boot in single user mode in any case, but nothing beyond that. I tried installing linux on that blank new drive and that worked fine and linux runs great on it. Running AHT, off the net, because I can't get that to run from anything else, only shows the expected error from the missing temperature sensor on the hard drive, because it's a genuine seagate non apple. So I expect all the system tests show nothing wrong with the machine, unless the AHT stops on the sensor error and doesn't finish the remaining tests, which I would assume wouldn't be the case. Resetting the pram hasn't done anything, despite having done it many times. The SMC has been reste many times, at first by having the machine go to the local apple authorized store for the hard drive recall (I got the machine back because I didn't want them to keep the original drive with my data on it). Everything seems to point to a healthy machine, although the missing firmware on the seagate drive causes the AHT error on the sensor, it runs linux just fine and it seems fine only until osx boots up to about 30% and stalls there. The only thing I could not try is to put it in target mode, because it has thunderbolt and not firewire, while I have an older laptop with firewire and not thunderbolt. I plan to locate a thunderbolt cable and ask someone I know to allow me to link up with their imac to see what I can do with the drive in that imac, but I suspect even if I managed to put a functional system on that drive, it won't boot any further that in any other boot method. So what else could it be then???? I'm out of ideas.