Upgraded the twins today. T420 got 16gb ram and a sled battery. 9cell + sled = 17hrs battery life. T480 got an extra 16gb of ram, up to 32gb. Happy with the
parts-quick 16GB DDR3 Memory for Dell PowerEdge T420 Server 2Rx4 RDIMM 1600MHz LV Memory Module at Amazon.com
CMS 16GB (2X8GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad T420 4177, 4178, 4180, 4236 Series - A13 at Amazon.com