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Amazon.com: 2 GB Graphics Video Card GPU Upgrade Replacement for Apple iMac Mid-2011 A1312 27 Inch Core i7 3.4 i5 3.1 Desktop Computer, New AMD Radeon HD 6970M HD6970M 2GB MXM Board
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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