Amazon.com: Original Graphics Video Card for Apple iMac Core i7 2.8 27-Inch Late 2009 A1412 MC507LL/A MC507 Desktop Computer, AMD ATI Mobility Radeon HD 4850 GDDR3 512MB 109-B91157-00, GPU Upgrade Replacement : Electronics
HoTecHon MXM 3.0 Type A X-bracket / GPU Support Platform (no screws) for iMac 27" Late 2009 to Mid 2011 Graphics Upgrade - AliExpress
For iMac 27" A1312 Mid 2009 2011 HD6970M upgrade NVIDIA GTX 765M 2GB Video Card | eBay
How To Flash A PC GPU With A Mac ROM For Your Late 2009 - Mid 2011 iMac - YouTube
For iMac 27" A1312 Mid 2009 2010 2011 upgrade NVIDIA K3100M 4GB GPU Video Card | eBay
iMac Late 2009 21.5" GPU upgrade - Apple Community
Amazon.com: Genuine Graphics Video Card for Apple iMac Late 2009 A1311 Core 2 Duo 3.06 21.5 Inch Desktop PC MB950LL/A MB950, AMD ATI Radeon HD 4670 GDDR3 256MB, MXM VGA Board GPU
Should I upgrade my Intel E7600 CPU for an E8600 in my iMac 27" late 2009? - Ask Different
Amazon.com: Valley Of The Sun Graphics Video Card GPU Replacement for Apple iMac Mid-2010 A1311 Core i3 3.06 MC508LL/A MC508 21.5 Inch Desktop Computer, ATI Radeon HD 4670 GDDR3 256MB, MXM VGA
Late 2009 iMac 27" Video Card Repair [4850 Bake] - YouTube