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Upgrading the graphics in our 2011 iMac (first attempt) - 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 :
Cracking Open the 27" Apple iMac (2011) | TechRepublic