How to Upgrade/Replace GPU Graphics Card on Mid-2011 21.5" iMac - YouTube
Baking a Graphics Card | macman860
gpu - Apple iMac mid 2011 Graphical Artifacts - Super User
GPU Video Heatsink 730-0630-A with Sensor Original iMac 27 inch A1312 2011 for Radeon 6770 6670 6750 - used original spareparts for Macs
How to Upgrade/Replace GPU Graphics Card on Mid-2011 21.5" iMac - YouTube
Amazon.com: Valley Of The Sun 2GB Graphics Video Card Upgrade for Apple iMac Mid-2011 27 Inch Core i5 MC814LL/A MC814 A1312 Desktop All-in-One PC, AMD Mobility Radeon HD 6970M Replacement Repair Parts :