HP VH638AT, 4 GB, 1 x 4 GB, DDR3, 1333 MHz, 240-pin DIMM HP VH638AT. Component for: PC/Server, Internal memory: 4 GB, Memory layout (modules x size): 1 x 4 GB, Internal memory type: DDR3, Memory clock speed: 1333 MHz, Memory form factor: 240-pin DIMM