iMac Intel 27" EMC 2390 Radeon HD 5750 Graphics Card - iFixit Store
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 Board Repair Parts : Electronics
iMac 2009 / 2010 / 2011 GPU upgrade — Fixing LED/LCD PWM brightness with an ESP32 | by Fixing Things | Medium
Amazon.com: Graphics Video Card GPU Replacement for Apple iMac Mid-2010 A1312 Core i5 3.6 MC510LL/A MC511LL/A 27 Inch 27" Desktop PC Computer, ATI Mobility Radeon HD 5670 GDDR3 512MB Genuine Parts :
Amazon.com: Original Graphics Video Card GPU Upgrade Replacement for Apple iMac 21.5 Inch Late 2011 Core i3 3.1 All-in-One Desktop PC MC978LL/A, AMD ATI Mobility Radeon HD 6750M, MXM VGA Board Repair
Would this be a bad GPU? iMac mid 2010 21.5” : r/mac
iMac Intel 27" EMC 2374, AMD Radeon HD 4850 Video Card Removal & Repair - iFixit Repair Guide