8GB Total memory using 2pc of 4GB 1333MHz Module 240pin dimm DDR3 10600. Lifetime warranty for exchange by Computer Memory Solutions Brand Computer Memory Solutions Guaranteed to work or you get all of your money back including shipping. Expansion: 2 Sockets Maximun Memory: 4 GB with 64-bit OS Compatible with Dell Vostro 260s Video Features If 4GB is installed, the recognized memory may be reduced to 3.5GB or less (depending on system configuration and memory allocation). Maximum configurations require a 64-bit operating system.