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How-To: Boost your Mac's speed and prolong its useful life with easy RAM upgrades - 9to5Mac
مغامر شارب قائد المنتخب imac 21.5 inch mid 2011 ram upgrade - tafraa.com
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iMac Intel 21.5" EMC 2428 CPU Fan Replacement - iFixit Repair Guide
How to Upgrade the RAM in Your iMac
How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com