16GB KIT (2 x 8GB) for Dell Studio Notebook Series XPS 16 (1640). SO-DIMM DDR3 Non-ECC PC3-8500 1066MHz RAM Memory. Genuine A-Tech Brand. at Amazon.com
4GB Compatible Memory Upgrade for Dell Studio XPS 13 (1340), Dell Studio XPS 16 (1640), (1645), (1647) DDR3 PC3-10600 RAM (PARTS-QUICK BRAND) - Walmart.com
Studio XPS 16 (1640) Parts & Upgrades | Dell Canada
Seifelden 2GB (2X1GB) Memory RAM for Dell Studio XPS 16 (1640) Laptop Memory Upgrade - Walmart.com
CMS 8GB (2X4GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Dell® Studio 16 (1640) Notebooks Ddr3 - A29 at Amazon.com