How-To: Boost your Mac's speed and prolong its useful life with easy RAM upgrades - 9to5Mac
Install memory in an iMac - Apple Support
How to install ram in an apple 27" imac (mid 2011) - B+C Guides
Installing and Upgrading Ram on a mid 2011 iMac (different size RAM) - Ask Different
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Install memory in an iMac - Apple Support
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Install memory in an iMac - Apple Support
How-To: Boost your Mac's speed and prolong its useful life with easy RAM upgrades - 9to5Mac