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iMac 2010 GPU in 2011 | MacRumors Forums
iMac 2009 to 2011 (A1311/A1312) Upgrade Guide – MacintoshMen
Upgrading the graphics in our 2011 iMac (first attempt) - YouTube
For iMac 27" A1312 Mid 2009 2011 HD6970M upgrade NVIDIA GTX 765M 2GB Video Card | eBay
How to Upgrade/Replace GPU Graphics Card on Mid-2011 21.5" iMac - YouTube