Amazon.com: 2GB Graphics Card GPU Upgrade Replacement for iMac 27 Inch Mid-2011 A1312 Desktop Computer Core i5 3.1 MC814LL/A MC814, AMD Radeon HD 6970M GDDR5 2 GB MXM Video Board Repair Parts :
Original Graphics Card GPU Replacement for Apple iMac 2009 Core 2 Duo 3.06 A1312 MB952LL/A 27 Inch Desktop PC Computer, ATI Mobility HD 4670 GDDR3 256MB 109-B80357-00, MXM Video Board Repair Parts:
Upgrade GPU and CPU for a late-2009 Imac | MacRumors Forums
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
Should I upgrade my Intel E7600 CPU for an E8600 in my iMac 27" late 2009? - Ask Different
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