Refurbished 27-inch iMac 3.8GHz 8-core Intel Core i7 with Retina 5K display - Apple (UK)
Upgrading an iMac GPU for METAL Support! Late 2009 – Mid 2011 Models - YouTube
Original For Apple Imac 27" A1312 Vga Card Gpu 216-0732019 Video Card Graphic Card 109-b90957-00 Hd4850 512mb Full Tested - Pc Hardware Cables & Adapters - AliExpress
iMac Graphics Card Replacement East Midlands Derby – UKSL MacLab
The optional Upgrades for the Apple iMac 27 are not worth it - NotebookCheck.net News
Apple iMac 27" A1312 (Late 2009) - VGA Chip ATI 216-0732026 | Fixshop
iMac Graphics Card GPU Overheating and Failure
Refurbished Apple iMac 21.5" 2010 Radeon HD 5750 512MB GPU+Heatsink, fits 2009, 2010, and 2011 iMacs
AMD Apple iMac 27" A1312 HD6790M 109-C29657-10 Graphics (No heatsink) FAULTY Graphics Cards
Upgrading the graphics in our 2011 iMac (first attempt) - YouTube
Apple iMac 24" A1225 Nvidia Video/Graphics Card 661-4664 GPU Replacement Service | eBay
2010 iMac GPU Upgrade to NVIDIA GTX 765M - YouTube