2011 iMac Graphics Card Upgrade | How to • Mac Expert Guide
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
Amazon.com: 2GB Graphics Card GPU Upgrade Replacement for iMac 27 Inch Mid- 2011 A1312 Desktop Computer Core i5 3.1 MC814LL/A MC814, AMD Radeon HD 6970M GDDR5 2 GB MXM Video Board Repair Parts :