iMac Not Booting

I am working on a 8, 1 iMac that a friend gave to me to troubleshoot. The device would not boot but would continuously run the spiral under the Apple logo and go no further. The superdrive would not keep discs in either so I replaced it. The computer would not boot to any OS DVD. I have made various USB install drives with Snow Leopard and Lion in an attempt to re-install the OS. On only one occasion I did get Lion to re-install on a re-partitioned drive. But when it rebooted to complete the installation of updates the original issue returned. One time I was able to go through the Lion install process and reboot after downloading the extra files but after the reoot it would not continue. On all other occasions when I try to boot from a confirmed good install USB the device would not boot to the media. In order to boot to the desired media I must hold the alt/option key at boot. I have not gotten the command+r key combination to work. I have confirmed the RAM is good. The hard drive has been confirmed good by running Seagate's SeaTools on the reconditioned drive. One unusual thing to note is that both Seatools and Seagate's Drive Detect software indicate that there should be an available firmware update. However, Seagate Technical Support says there is none and this message is an error in the program. My leaning is that the issue is caused by system-board failure failure - especially since I have tried multiple hard drives. All my troubleshooting experience is on Windows machines so I have come here for some help.

G'day and welcome to the forums.

Seagate's tools are strictly Windows only. If you got Lion OS X.7 installed, again try and boot from Recovery by holding down Command and R immediately after the chime. If it loads, leave the Installer, go into utilities > Disk utility and run repair Disk and see what is reported. If not your diagnosis of logic board may be correct and off to Apple if the owner thinks this is worthwhile An 8.1 is a 2008 model. There was a Seagate drive return offer available from Apple so check that out.

http://www.apple.com/au/support/imac-harddrive/

harryb2448 said:

G'day and welcome to the forums.

Seagate's tools are strictly Windows only. If you got Lion OS X.7 installed, again try and boot from Recovery by holding down Command and R immediately after the chime. If it loads, leave the Installer, go into utilities > Disk utility and run repair Disk and see what is reported. If not your diagnosis of logic board may be correct and off to Apple if the owner thinks this is worthwhile An 8.1 is a 2008 model. There was a Seagate drive return offer available from Apple so check that out.

Apple - Support - iMac 1TB Seagate Hard Drive Replacement Program

Click to expand...

Thanks. Your suggestion reminded me that I did indeed run the disk check in the disk utility tool when partitioning the drive. I would try your suggestion regarding the command R combination if it worked. I tried it multiple times but no options came up. The recovery drive did show up with the system partition after the Lion reinstall when holding down the option/alt key when booting. I apologize for missing that step in my description.

As Harry pointed out the machine is either a 20" or 24" early 2008 iMac. From your description of the symptoms and from what you've already done to repair it, it would appear to be a logic board (mother board) failure of some sort. The 24" models came equipped with either an ATI Radeon or nVidia GPU. The nVidia GPUs of that year were problematic especially for the Mac portable computers (MacBook Pro). If it's a logic board failure of some sort, it may not be worth repairing considering the age of the machine.