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 Parts : Electronics - Amazon.com
Amazon.com: 2GB Graphics Card GPU Upgrade Replacement, for Apple iMac 27" 2011 Desktop Computer A1312 Core i7 3.4 MD063LL/A MD063, AMD Radeon HD 6970M GDDR5 2 GBS, MXM VGA Video Board Repair
For iMac 21.5" A1311 Mid/Late 2011 6770 AMD upgrade Nvidia K610m 1GB Video Card | eBay