How to replace RAM in a laptop - replacing RAM in a Lenovo / IBM T400 laptop - YouTube
T500 - RAM upgrade resulting in many Beeps on boot - Thinkpads Forum
OFFTEK 4GB Replacement Memory RAM Upgrade for IBM-Lenovo ThinkPad R400 Series (DDR3-10600) Laptop Memory at Amazon.com
Lenovo Thinkpad R400 – Azrex Technology
CMS 8GB (2X4GB) DDR3 8500 1066MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad T400 2764, 2765, 2766, 2767, 2768 - A35 at Amazon.com
Lenovo ThinkPad Laptop R400 14.1" Windows 10 4GB RAM 320GB HDD DVD WIFI C2D
4GB Team High Performance Memory RAM Upgrade Single Stick For Lenovo ThinkPad R400 Series R500 Series L aptop. The Memory Kit comes with Life Time Warranty. at Amazon.com