Video Graphic VRAM Card VGA GPU for Apple iMac 27 inch A1312 HD6970 HD6970m 1GB 109-
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
Apple Initiates Video Card Replacement Program for Radeon HD 6970M Equipped Mid-2011 27” iMacs