2011 iMac CPU Upgrade - will a Xeon work? Also how about a k2100m at the same time! - YouTube
The CPU Selection - The 27-inch Apple iMac Review (2011)
2011 iMac CPU & SSD upgrade in Detail | 2020 - YouTube
Apple iMac 27 inch A1312 2011 Socket LGA1155 Logic Board Motherboard 639-2188 | eBay
21.5 iMac Mid 2011 12,1 A1311 820-3126 Logic Board Core I5 "CPU Not In - Part Haven
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 :
How to Install the Motherboard in Apple iMac (27", mid 2011) - YouTube