Amazon.com: Genuine Graphics Video Card Replacement AMD Radeon HD 6970M GDDR5 1GB 109-C29657-10 for Apple iMac 2011 27" MC814LL/A MD063LL/A A1312 Desktop PC Computer, MXM VGA Board Repair Parts Full Tested :
NEW Apple iMac 27" A1312 mid 2011 AMD Radeon HD 6970M 2GB DDR5 VGA Video Card | eBay