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OFFTEK 4GB Replacement Memory RAM Upgrade for IBM-Lenovo ThinkPad T400 (6475-xxx) (DDR3-8500) Laptop Memory at Amazon.com
Lenovo T400: How to upgrade the RAM - YouTube
Tutorial: Upgrading the Ram on a Lenovo or IBM Thinkpad Laptop (in 1080P!) - YouTube
IBM Lenovo Thinkpad T400, T61 Laptop 1.8 GHz 4 GB Ram Windows XP pro SP3 WiFi – ASA College: Florida