2011 iMac 21.5” CPU Upgrade Full Tutorial! - YouTube
MacBook Air i5 vs i7 – Is the upgrade worth it? – Mac Crazy
MacBook Pro Upgrade Guide
Amazon.com: Valley Of The Sun New 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 :
The Definitive Classic Mac Pro (2006-2012) Upgrade Guide