Hi Scot, There are unfortunately no quick diagnostic approaches with kernal panics. It could also be the hard drive and/or the RAM. I am currently puzzling over a 2011 iMac with a Kernal panic that occurs as soon as I attempt to start Disk Warrior. With 4 machines you could always try the mix and match method. It may take some time, but it could save you a few bucks by not bringing it to a Mac specialist. Also try starting up but first try removing any third part RAM that might be installed. Have you tried the hardware test that comes with your Macs original disks? Bill