How to upgrade RAM / Memory on a 2010 iMac Core i3 i5 i7 (21.5in & 27in) - YouTube
Installing additional SSD in Mid-2010 27" iMac
Apple MC508LL/A 21.5" iMac Computer Core i3 3.06 GHz 4GB RAM 500GB HD Mid- 2010 | RecycledGoods.com
iMac 27" Mid 2010 i7 CPU 20GB ram 1TB HD, OSX High Sierra, 4k USB camera giving garbage pattern on camera feed to Lightburn - LightBurn Hardware Compatibility - LightBurn Software Forum
CMS 16GB (4X4GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I3 3.06 21.5-Inch (Mid-2010) - A28 at Amazon.com
A-Tech 16GB Kit (2x8GB) DDR3 1066MHz / 1067MHz PC3-8500 SODIMM RAM for Apple MacBook (13 inch, Mid 2010), MacBook Pro (13 inch, Mid 2010), iMac (27 inch, Late 2009), Mac Mini (Mid 2010) at Amazon.com
A-Tech 32GB (4x8GB) RAM for Apple iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET