Amazon.com: 2GB Graphics Video Card Replacement for Apple iMac Mid-2011 27 Inch A1312 Core i7 3.4 MD063LL/A MD063 Desktop PC Computer, ATI Radeon HD 6970 GDDR5 2 GB, New GPU Upgrade Repair
Late 2009 iMac 27" Video Card Repair [4850 Bake] - YouTube
Amazon.com: Original Graphics Video Card for Apple iMac Core i7 2.8 27-Inch Late 2009 A1412 MC507LL/A MC507 Desktop Computer, AMD ATI Mobility Radeon HD 4850 GDDR3 512MB 109-B91157-00, GPU Upgrade Replacement : Electronics
iMac Intel 27" EMC 2374, AMD Radeon HD 4850 Video Card Removal & Repair - iFixit Repair Guide
Original Graphics Card GPU Replacement for Apple iMac 2009 Core 2 Duo 3.06 A1312 MB952LL/A 27 Inch Desktop PC Computer, ATI Mobility HD 4670 GDDR3 256MB 109-B80357-00, MXM Video Board Repair Parts: