I'm writing as I'm experiencing a weird issue with my iMac I've never run into before.
I'm on a 27" iMac i7 3,4GHz with 16GB RAM and a AMD Radeon 6970M 1GB GPU
My iMac started crashing with glitchy, vertical and horizontal lines. When it does these crashes whatever audio has been playing is "looped" in a very typical crash'y behaviour. I've been following different topics like a madman and I'm pretty sure it has to do with the GPU temperature that sometimes reach 90-95 degrees celcius (which is close to 203 fahrenheit). Opening the windows and using SMCFanControl to keep the fans spinning a bit seems to help the issue, but it's not really a durable solution to have my computer sounding like a vacuum cleaner just to be able to use it.
For the record I do no graphics intensive tasks and do only music production on my computer.
I've never experienced these problems in Snow Leopard, but then again I haven't had more than a few Kernel Panics in Lion - the computer does feel noticeably hotter in Lion though. The GPU crashing problem is relatively new, and I'm considering dust to be an option (even though my house is relatively dust free) - but I'm not the biggest fan of (and techsavvy enough to) cranking my screen open to vacuum clean its guts.
I attached a picture taken with my cell of how the screen looks during these crashes.
I'm dying to find out what this could be. Keep in mind this started about 5 days ago, and have never been an issue before. I haven't updated any software prior to the symptoms except for Logic Pro, but it would seem weird to me that an audio application is causing GPU overheating, and besides the GPU is still very hot when I'm not using Logic.