roartj :
Since it is a iMAC it´s all in the monitor, and my warrenty would no longer be valid..and it´s only 2months old...maybe it´s not designed for games??? (I must admit I am new to the mac world...) :-/
I have had the same problem with my iMac, early 2008 model, 3.06ghz, 4gb ram, with 512 mb nvidia video card. I think that Toca race driver (and x-plane) finally crashed it. Luckily, I had the extended warranty, so it didn't cost me a cent to fix it. However, apple did about $1300 worth of repairs the first time. It happened one day later, and they spent about another $1,600 fixing it. (I'm sure it didn't actually cost them that much, that's just what the invoices showed.) They replaced the video card 2 times, fans, hard drives, and a bunch of other things, I don't have the invoices in front of me, and I'm not a computer expert. They, the apple geniuses, never really seemed like they knew what was wrong, and their egos seemed to get in the way of giving me a good explanation of what happened to it. So, they basically just replaced everything but the frame of the computer, taking the shotgun approach. All I can suggest is back up your entire system before it crashes, and get the extended warranty, so you don't lose your computer because of repair costs. I know this isn't expert advice, and is just anecdotal, but, I've been through it before. Backing up system and getting extended warranty would be my advice.