Burn the VGA and Fix your iMac - Don't Pay Shitty Problems!!! - YouTube
Apple upgrades its 27" iMac with 10-gen Intel CPUs, new AMD GPUs and doubles RAM capacity: Digital Photography Review
Upgrading an iMac GPU for METAL Support! Late 2009 – Mid 2011 Models - YouTube
2 GB Graphics Video Card GPU Upgrade Replacement for Apple iMac Mid-2011 A1312 27 Inch Core i7 3.4 i5 3.1 Desktop Computer, New AMD Radeon HD 6970M HD6970M 2GB MXM Board Repair Parts
iMac 2009 to 2011 (A1311/A1312) Upgrade Guide – MacintoshMen
Upgrading the graphics in our 2011 iMac (first attempt) - YouTube