I found this post on another forum which seems to suggest it's possible to replace the GPU? http://forums.appleinsider.com/showpost.php?p=1526374&postcount=134 I'm kind of confused as I thought the 5970 is a desktop GPU? Also I thought it wasn't possible to replace the card anyway cause it uses a custom shape or something? Can anybody clarify this for me? Is it possible? If it is then that'd be amazing, with a 5970 the iMac would be an all-around powerhouse, no longer lacking in one department.