HP B1S54ATR, 8 GB, 1 x 8 GB, DDR3, 1600 MHz, 240-pin DIMM HP B1S54ATR. Internal memory: 8 GB, Memory layout (modules x size): 1 x 8 GB, Internal memory type: DDR3, Memory clock speed: 1600 MHz, Memory form factor: 240-pin DIMM