For iMac 27" A1312 Mid 2009 2011 HD6970M upgrade NVIDIA GTX 765M 2GB Video Card | eBay
Amazon.com: Original Graphics Video Card GPU Upgrade Replacement for Apple iMac 21.5 Inch Late 2011 Core i3 3.1 All-in-One Desktop PC MC978LL/A, AMD ATI Mobility Radeon HD 6750M, MXM VGA Board Repair