Apple iMAC 27" A1312 Mid 2011 AMD Radeon HD 6970M Video Card 1GB 109-C29657-10 | eBay
Amazon.com: Valley Of The Sun 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 :
Apple iMAC 27" A1312 Mid 2011 AMD Radeon HD 6970M Video Card 1GB 109-C29657-10 | eBay
AMD Radeon HD 6970 1gb video upgrade to 2gb | MacRumors Forums