How to Upgrade/Replace GPU Graphics Card on Mid-2011 21.5" iMac - YouTube
Apple iMac | Apple Computers | Extended Warranties Available
OWC DIY Kit for 2009 - 2011 27" iMac optical bay:... at MacSales.com
Apple iMac i5 2011 review
USB 3.0 for iMac mid 2011 | MacRumors Forums
2011 iMac Graphics Card Upgrade | How to | Mac Expert Guide
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 :