Failing Apple iMac Mid 2011 A1312 AMD HD 6970M 1GB GDDR5 Video Card 661-5968 109-C29657-10 . Failing to boot properly. Rarely boots all the way but freezes within minutes.
Also throwing in :
Apple 109-C29557-00 iMac A1311 2011 AMD Radeon HD 6750 512mb Video Graphics Card. No video at all on A1312 2011. Not sure if completely dead or not compatible.