I just acquired a Mid 2011 27" iMac. It has a Core i5-2400, 4GB DDR3 (going to upgrade to 16GB) and a 1TB Seagate HDD. The GPU is currently bad in this machine, and I have only been able to get it to boot to a usable desktop 2 times in the past week. Are there any GPUs that can be put in these machines that are more reliable than the stock Radeon HD 6970M card? I am not looking for a lot of performance (this iMac will eventually be used as a general purpose client machine for managing the servers I have for testing), and the current GPU is plenty powerful for my needs. I'm just hoping something more reliable exists. I am going to perform the GPU replacement myself as I am more than comfortable working in an iMac. Thanks for any suggestions!