My friend brought me his 2008 24" iMac Intel Core 2 Duo 3.06Ghz - A1225 to fix up so he could sell. It was acting funny. Start up would always be a kernel panic, and when installing OS from Disc 1, the screen would get lines and choppy looking. I was baffled and so took it in to the genius bar for diagnosis. They said they suspected the HD was bad and the graphics card was dodgy, estimate was $400 to fix which is all it was worth on a good day for trade-in online. My friend asked me to do my best on my own. I ran a hardware test off disc 1, it passed. I ran the extended HD test, and the screen got all funky toward the end, but I could still see that it passed. I pulled out the HD and ran a battery of stress tests on the drive with Drive Genius and the drive is perfectly fine. (I figure that with it being out of warranty the Genius' couldn't do more than a cursory diagnostic without a commitment on my part to pay) So in the end I reformatted the HD and put everything back together. I ran the Hardware Test again, same results. I attempted to start from disk 1 to reinstall OS. I only got as far as the gray screen with Apple and gear when it froze. I repeated the process several times with no change. Each time the screen looks fine. At this point I think its the logic board. Would like to get your thoughts and ideas. I know the machine is nearly "vintage" but its a fun and fascinating project for me. If I can fix it and he can pickup some money on a trade-in then awesome! If not and we can sell the good stuff for parts then that'd be great too.