Today picked up a $20 2011 iMac 27” with working gpu too! : r/mac
Shop Imac 2011 Graphics Card Upgrade | UP TO 51% OFF
Amazon.com: 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
iMac 2009 to 2011 (A1311/A1312) Upgrade Guide – MacintoshMen
Shop Imac 2011 Gpu | UP TO 52% OFF
Amazon.com: Valley Of The Sun 2GB Graphics Video Card Upgrade for Apple iMac Mid-2011 27 Inch Core i5 MC814LL/A MC814 A1312 Desktop All-in-One PC, AMD Mobility Radeon HD 6970M Replacement Repair Parts :
Upgrading the graphics in our 2011 iMac (first attempt) - YouTube
Amazon.co.jp: Original Graphics Card GPU Upgrade Replacement, for Apple iMac 21.5" Late 2011 Core i3 3.1 Desktop PC MC978LL/A, AMD ATI Radeon HD 6750M MXM VGA Graphics Board Repair Parts : Computers