RAM upgrade considerations for iMac systems - CNET
How to Upgrade Memory in a 21.5-inch or 27-inch iMac (Mid 2010) - YouTube
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
A-Tech 16GB (2x8GB) RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Install memory in an iMac - Apple Support
How to upgrade RAM / Memory on a 2010 iMac Core i3 i5 i7 (21.5in & 27in) - YouTube
iMac Mid-2010 27 inch (A1312) SSD and RAM disassembly and upgrade - Much FASTER! - YouTube